The markdown and repo list examples are pretty simple and can easily be
moved to be inline samples so that they render as part of the packages
godocs.  This helps make them more visible even if they won't run in the
browser.  The basic auth example requires interacting with the user, so
leaving it where it is.  Future examples should be included inline
whenever possible.

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.

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

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

               MMM.           .MMM
               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~~~~
            ~~~~~~==~==~~~==~==~~~~~~
             ~~~~~~==~==~==~==~~~~~~
                 :~==~==~==~==~~

notably, this also updates client.Do() to handle non-JSON response
bodies by passing an io.Writer as the final argument, v.