Facebook Support.

* Modified setup.sh to handle .pkg files, since that's how the facebook SDK is packaged.
* Added Facebook config Info.plist (and re-ordered items so URL Schemes are at the bottom,
  since you need to modify one).
* Hooked up facebook login button with super simple workflow.
Tweak setup.sh (undo some renames, remove a leftover 'zip' reference)
Merge pull request #2 from firebase/login-v2-facebook

Facebook Support.