Implements the Merge API

http://developer.github.com/v3/repos/merging/
Merge via API. Whoa, meta.
Version bump
Support unauthed rate limited requests

Refs #128. Now you can set Octokit.client_id and
Octokit.client_secret to make unauthenticated while using
higher rate limits for your OAuth app if available.
Implements Status API

http://developer.github.com/v3/repos/statuses/
Version bump
Retrieve a pull request's commits
Merge pull request #131 from pbyrne/pull-request-commits

Retrieve a pull request's commits
Version bump
Add test for octokit error messages
Allow overriding the Host header in API requests.

This supports scenarios where the GHE instance is behind a proxy that
interferes with normal API functionality (e.g. authenticates with
OAuth).

In order to use the API when GHE is behind a proxy like that, you need
to hit it using a different (internal) hostname. However, as of version
11.10.280, GHE redirects all non-canonical hostname requests to the
canonical version. This breaks using a different hostname for API
requests.

This commit enables access using a different hostname by overriding the
Host header so that GHE does not perform the redirect.
merge pull request
Version bump
Add Stars support.
Version bump
Merge branch 'master' of https://github.com/bjeanes/octokit into host-header-override
Version bump
Merge pull request #132 from bonsaiben/faraday_response_error_tests

Add test for octokit error messages
Add CUD operations for commit comments. Closes #114

Add create_commit_comment, update_commit_comment and delete_commit_comment
Fix doc urls.