Adding support for --depth clone argument.
Fixed brackets in examples for gitpush gitpull and gitmerge
Merge pull request #52 from thijsvdanker/master

Fixed brackets in examples for gitpush gitpull and gitmerge
Remove incomplete contributors list: use github.

There's no point in having an unmaintained and incomplete list here.
Let's just refer to github for this info.
Remove 0.8 from testing.
Merge pull request #49 from ajmichels/clone-depth

Adding support for --depth clone argument.
Remove the isNaN check, allow depth 0.

Relates to #49.