Implement merging a pull request
Fix GitTree parsing on submodule paths
Add extra auth functions for Trees
Merge pull request #67 from nataren/merge_pull_request

Implement merging a pull request and checking if it has been merged.
Merge pull request #69 from charleso/topic/tree-auth

Add extra auth functions for Trees
Merge pull request #68 from charleso/topic/tree-submodule-url

Fix GitTree parsing on submodule paths
Merge master