update CreateTeam and EditTeam to pass preview media type if
Team.Privacy is set.

Ref #187

- allow setting permission when adding a team repository
- update IsTeamRepo to return a *Repository instead of a bool, since the
  Repository contains the permission data for the team.  This is a
  BREAKING CHANGE, however I don't think this is an often used method.
- update docs for setting the team permission when creating or editing a
  team.

Ref #187

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

GitHub occasionally changes the IP addresses from which GitHub Pages
websites are served. For users of the service, they must upgrade any A
records to these IP addresses to continue using the service. This patch
provides this data in the `APIMeta` struct as the property `Pages` and
populates from the /meta endpoint.

Release Announcement:
https://developer.github.com/changes/2015-06-11-pages-a-records/

Fixes #212.

ocd kicking in :)

Supports the updated starring API as mentioned in issue #188.

There is now a new struct called StarredRepository which holds a Repository and the new `starred_at` timestamp.
For now there is a special media type to request the new API. I've added a TODO for it to be deleted when the new API fully launches.

There's no way of serializing/requesting an empty required_contexts that
is needed for bypassing the commit status checks for the ref.

It's a breaking change but will allow to serialize an empty array and
omit empty value as expected.

Fixes #185.

Memberships API is now official.

https://developer.github.com/changes/2014-09-16-finalizing-the-organization-and-team-membership-apis/

Fixes #192

Deployments API is now official.

https://developer.github.com/changes/2014-11-25-the-deployments-api-is-official/

Fixes #189.

Both have been deprecated.

Fixes #190.

- AddTeamMember: https://developer.github.com/v3/orgs/teams/#add-team-member
- RemoveTeamMember: https://developer.github.com/v3/orgs/teams/#remove-team-member

Also:
 - add PingHook to RepositoriesService
 - move ListServiceHooks to Client, since hooks are no longer just for
   repos.  Leave behind Repositories.ListServiceHooks for backwards
   compatibility

Fixes #178

The client_id and client_secret URL variables,
containing sensitive app information, are leaked
to users if the Go error is returned to them. To
prevent this, sanitizeURL redacts the fields from
ErrorResponse's Error method. Therefore making the
error message safe to expose to users.

As per https://developer.github.com/v3/pulls/#list-pull-requests

Renamed test method

Changed from PatchUrl to PatchURL

The RepositoryContent struct doesn't quite map to the API because it is
missing a download link.  This link is very useful because while the API
doesn't allow large files to be downloaded, the link allows the raw
files to be downloaded outside the API.

The issue is that the JSON tags on the contents struct were wrong.  They
were missing the underscore.

Unfortunately this is a breaking change, and having a pointer to a slice
is not very common, but is needed in this case to allow clearing an
issue's labels.

Fixes #181

This integer exposes the number of comments that have been posted for that commit on GitHub.

It is documented at https://developer.github.com/v3/repos/commits/.

https://developer.github.com/v3/repos/releases/#create-a-release

Fixes #159

this method actually returns RepositoryCommits (go-github's term for
this, not GitHub's) rather than Commits.  They are very, very close in
structure (which is likely why this has gone unnoticed for so long), one
of the primary differences being that RepositoryCommits exposes the
GitHub identity of the commit author and committer if possible.

Add ListOptions to PullRequestListCommentsOptions and
IssueListCommentsOptions

fixes #143

These changes are strictly violations of any style guide (I don't
think?), but are just to make tests in go-github more consistent,
particularly in use of 'got' and 'want' vars.  In doing this, I found
several places where those two got reversed in the error message (hint:
'got' always comes first in go)

okay, so these aren't really that useful buy hey, why not? :)

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               MMMMMMMMMMMMMMMMMMM
               MMMMMMMMMMMMMMMMMMM      __________
              MMMMMMMMMMMMMMMMMMMMM    |          |
             MMMMMMMMMMMMMMMMMMMMMMM   | Ship It! |
            MMMMMMMMMMMMMMMMMMMMMMMM   |_   ______|
            MMMM::- -:::::::- -::MMMM    |/
             MM~:~   ~:::::~   ~:~MM
        .. MMMMM::. .::::. .::MMMMM ..
              .MM::::: ._. :::::MM.
                 MMMM;:::::;MMMM
          -MM        MMMMMMM
          ^  M+     MMMMMMMMM
              MMMMMMM MM MM MM
                   MM MM MM MM
                   MM MM MM MM
                .~~MM~MM~MM~MM~~.
             ~~~~MM:~MM~~~MM~:MM~~~~
            ~~~~~~==~==~~~==~==~~~~~~
             ~~~~~~==~==~==~==~~~~~~
                 :~==~==~==~==~~