Make \usepackage{gitinfo} work

First, set a global template directory, according to http://stackoverflow.com/a/8842663/323100
Then, do the setup as in `texdoc gitinfo` (with the global hooks folder just set above).
Don't forget to `chmod 755 post-*` in '~/.git_template/hooks/`
Checkout, commit and merge away.
Add `\usepackage{gitinfo}` and `\gitAbbrevHash` to your .tex documents