Add boot2docker config
Prefer Homebrew Git over Mac OS X Git

Moving /usr/local/bin in front of /usr/bin to use the
binaries installed via Homebrew as the default.

This is change was sparked by the recent update to git clients.
Using git client from Homebrew includes the fix over the default
that is shipped with Yosemite.

Annoucement:
https://github.com/blog/1938-vulnerability-announced-update-your-git-clients