Fix all ModTimes
Get rid of GitRepositoryNative
Update tests
Rework ModTimes to use git/hg instead of os.Stat
Fix Mercurial bug; use --template instead of -T

Mercurial 2.0.2 on Travis doesn't have -T. It needs --template instead.
Merge pull request #6 from Southern/devel

Fix ModTimes and get rid of GitRepositoryNative