Add git HEAD

[travisjeffery]

Hey,

Now people can install Git's latest development version via brew install git --HEAD.

Thanks,

Travis

[jacknagel]

This should probably point at either the kernel.org repository or https://github.com/git/git.git

[travisjeffery]

No, it should not. Check Git's download information on the homepage: http://git-scm.com/download

github.com/git/git is just mirrors gitster's (the maintainer of git) repo.

[jacknagel]

The list that Junio sends out in "a note from the maintainer" lists these:

git://git.kernel.org/pub/scm/git/git.git/
git://repo.or.cz/alt-git.git/
https://github.com/git/git/
https://code.google.com/p/git-core/
git://git.sourceforge.jp/gitroot/git-core/git.git/
git://git-core.git.sourceforge.net/gitroot/git-core/git-core/

I would prefer that we use the kernel mirror.

[travisjeffery]

I'll do github.com/git/git but I am not a fan of kernel.

I've updated the commit.

[jacknagel]

Pulled.