fixes #274

This adds support and integration tests for editing branch protection.

For more information about the preview see here:
https://developer.github.com/changes/2015-11-11-protected-branches-api/

This adds only retrieving the information and not setting it. Setting
will come in a later commit (if that one here is okay).

I tried to follow the naming guidelines as much as possible and
hopefully I made it right the first time. :-)

These changes are now official, so the custom media type is no longer
needed.  This does go ahead and remove RepositoryListOptions.IncludeOrg
which was being used to trigger the custom media type.  Even though this
is a breaking change, it was only in for a month and I don't think it
was too widely used during that time.

Fixes #219
/cc @captncraig who may have been using this

Change-Id: Ib54ced78c51a9c4e54e470136d36f91bf4716e8c

This is required for non-owners to create organization repos on github.

Includes additions to User, Organization, Repository, and Gist.  Some
minor changes to existing fields based on changes in the v3 API (for
example, Gist.User became Gist.Owner).  Most everything else is new
additions.

refs #103

This includes all of the methods mentioned in this blog post:
https://developer.github.com/changes/2014-03-18-paginating-method-changes/
as well as a handful of others I found.  Sadly, this is a breaking
change for many of these methods because it changes the method
signature, but with yesterday's API change these methods are now broken
anyway. :(

- Repositories.Delete
- Repositories.ListTeams
- Repositories.ListTags
- Repositories.GetBranch

this change also includes some additional minor code cleanup

fixes #58

this only updates a few user and repo functions just to establish the
calling pattern.  closes #56 (which also includes a little more
background)

This provides somewhat reasonable string representations of GitHub
structs.  This is specifically designed for this library and takes a
number of shortcuts where it can, so is not suitable as a general
purpose solution.  That said, I am exporting this function because it is
useful for things like printing out slices of GitHub structs, as can be
seen in examples/example.go.

I am certainly open to suggestions for what exactly the stringified
output should look like.  Currently, I think I've found a reasonable
compromise between fmt's "%v" and "%s" output.

Like a51d6b4303, this change makes me sad, mainly because it is a
breaking change for all clients, and makes common tasks like reading
data out of structs slightly more work, with no direct benefit. Notably,
developers will need to make sure and check for nil values before trying
to dereference these pointers.  Sadly, the change is still necessary, as
is more fully explained in issue #19.  We can make the nil pointer
checks a little easier by adding some Get* funcs like goprotobuf does.

I spent a lot of time over the last few weeks exploring this change
(switching fields to pointers) versus the much larger change of using
protocol buffers for all GitHub data types.  While the goprotobuf
library is very mature and feature-rich (it's used heavily inside of
Google), it's the wrong tool for this task, since we're not actually
using the proto wire format.  While it does address the immediate
concern in #19, it makes way too many other things terribly awkward.

One of the biggest drawbacks of this change is that it will make the
string output from fmt.Printf("%v") next to useless, since all pointer
values are displayed as their memory address.  To handle that, I'll be
writing a custom String() function for these structs that is heavily
inspired by goprotobuf and internals from go's fmt package.

The truth is, this change makes me sad.  It's a breaking change
for all clients and it adds more complexity to the library surface.  In
most cases, clients will simply drop the Response object on the floor
(which is actually all the library itself was doing before this
change... now we're just pushing that off to the client).

Initially, the Response object will be primarily of interest for
functions that return paginated result sets, since the Response.NextPage
field is the only way to know for sure if there are more pages that
should be fetched.  And this is really the cleanest way to get at that
data, so in that respect this change isn't so bad.

It's also worth noting that returning the raw Response object makes a
lot more since in a GitHub library than it may in others, given how
GitHub makes liberal (read: proper) use of HTTP request and response
headers.  Other APIs, like Google's various APIs for example, tend to
push things like pagination links into the response body.  While this is
certainly less of a purist view in terms of REST, it does make the lives
of client developers a lot easier, since then the response body contains
everything you need to know.  But whatever; this is how GitHub rolls, so
we'll roll right along with them.  (Somewhat ironically we are ignoring
the RESTful links in the GitHub response bodies, since we're actually
calling the API in an RPC style and don't do anything with those links.)

We still don't have an easy way to set arbitrary request headers, but
that's a problem for another day.

Fixes #22

Added support for manipulating webhooks for repositories

Repository service:
    ListLanguages   : Allows a user to list the languages for a repository
Activity service:
    ListStarred     : Allows a user to list the starred repositories for a user

Added a timestamp struct to handle different incoming time formats from
GitHub. Only modified the repo struct to reflect this new time struct
for now since it is currently the only location I am currently aware of
where this is an issue.

Issue: #1

Since the library has received external contributions, Google is no
longer the sole copyright holder.  Update the boilerplate at the top of
each file to reflect that, and add AUTHORS and CONTRIBUTORS files to
track this information.

golint doesn't like the underscore in "url_"

Users.List renamed to Users.ListAll to align with the forthcoming
Repositories.ListAll method.

This now aligns with the (pretty strong) golang convention of the
package name matching the path basename

- standardize on "url_" for internal vars rather than "urls" or "url"
- move var definition closer to first use in several tests
- add .gitignore for test binary

This commit adds the core library funcationality and establishes the
general calling style and testing structure.  Only a few GitHub API
methods related to organizations and repositories are included in this
first commit, mainly to cement the calling style.