Allow gitpython gitfs_provider to use git shas as envs

This only works so far for the fileclient, it will not work in the top
file. Additional work needs to be done to enable sha envs to be found by
the top file.
Merge pull request #10088 from terminalmage/2014.1

Allow gitpython gitfs_provider to use git commit SHAs as envs (2014.1 branch)