Add back the Google Play Services JAR
Fix AsyncTask to call .execute()
Add login activity that kind of sucks still

But bedtime!
Add some more to the LoginActivity
Abstract some stuff from LoginActivity -> GoogleAuth

Utility classes FTW. One weird thing is that the LoginActivity has to
proxy its onActivityResult method through to the GoogleAuth class, but I
guess things could be worse.
Merge pull request #2 from ted27/master

User Auth changes