see pillar.example for configuration

This state downloads formulas from git repositories and ensures
that they are recorded in the file_roots setting.

Gitfs for the minion is possible with salt 2014.7
Updated config _defaults.conf and pillar with example
Tested it on Archlinux with salt-call --local state.highstate

https://github.com/saltstack-formulas/salt-formula/issues/64

Fixes issue where a gitfs remote that has no child options would cause an
error. Also fix up bad yaml in pillar example.