Add support for npm

[piranna]

As stated at NodeOS/NodeOS#67 (comment), add support to make gitkit capable to be used by npm as a valid git cli command. Needed functionality is:

• git config --get remote..url
• git rev-list -n1 master
• git checkout [something]
• git clone [param] [param]
• git clone --template=[value] --mirror [param] [param]

[dbkaplun]

+1

[TylerLeonhardt]

+1

[mitsukaki]

+1

[billlibinyan]

+1