add git::Repository tests

[danieleades]

the git module of this library is currently untested. That should probably be addressed!

[danieleades]

#41 adds unit tests for pushing and pulling between local repositories.

some integration tests need to be added to test ssh authentication.

• these tests will depend on docker, and will not be run by default
• these tests will be failing initially, as this repo does not yet support authentication

[OverkillGuy]

See https://gist.github.com/OverkillGuy/d110f7dc1137b1bbe5b275e43ffae942 for my stab at launching gitolite over docker, hope that helps