Enable setting post thumbnails on posts

See #272

git-svn-id: http://gsoc.svn.wordpress.org/2013/rmccue/trunk@2276 f69abe3c-2ee2-4550-9a6d-17bd458115be
Separate each set of endpoints via filters

This creates a much larger separation between the different post types, and is
more indicative of how these should be used in plugins.

git-svn-id: http://gsoc.svn.wordpress.org/2013/rmccue/trunk@2277 f69abe3c-2ee2-4550-9a6d-17bd458115be
Check that we can read posts correctly

See #272

git-svn-id: http://gsoc.svn.wordpress.org/2013/rmccue/trunk@2278 f69abe3c-2ee2-4550-9a6d-17bd458115be
Show attachments with the inherit status

This is kind of hacky, but means we don't have to override the whole getPosts()
method from the posts endpoint instead.

See #272

git-svn-id: http://gsoc.svn.wordpress.org/2013/rmccue/trunk@2279 f69abe3c-2ee2-4550-9a6d-17bd458115be
prepare_post() no longer takes fields

See #328

git-svn-id: http://gsoc.svn.wordpress.org/2013/rmccue/trunk@2280 f69abe3c-2ee2-4550-9a6d-17bd458115be
Check for an error before adding more data

git-svn-id: http://gsoc.svn.wordpress.org/2013/rmccue/trunk@2281 f69abe3c-2ee2-4550-9a6d-17bd458115be
Override the links for media

See #272

git-svn-id: http://gsoc.svn.wordpress.org/2013/rmccue/trunk@2282 f69abe3c-2ee2-4550-9a6d-17bd458115be