Updated the routes for Statuses

The routes for the Statuses section have been updated to reflect the
current version at https://developer.github.com/v3/repos/statuses/
don't use beta API by default.
adds statistics
Merge pull request #207 from danthareja/stats

Adds statistics methods to repo
Merge pull request #196 from headlessme/master

don't use beta API by default.
Add support for globally configurable headers. Implementation idea from @greggman
Allow for empty strings in create-blob API call
Merge pull request #194 from rmhartog/commit_statuses

Updated the routes for Statuses
re-generated source files
bump version to v0.2.3
Fix markdown render method
Clean up markdown render method
Merge branch 'feature/markdown'