Improve comments
Be more precise about the sexplib dependency
Better handling of bare/non-bare clone
Expose the backend kind
Expose Git_unix.Sync.IO
Simplify the compilation of tests
Fix typo in mirage tests
Update CHANGES
Merge branch 'master' of github.com:mirage/ocaml-git

Conflicts:
	CHANGES
	setup.ml
Bump version
Merge pull request #30 from samoht/master

Minor API improvements