Updating demo application to include Twitter/Password and support Firebase Login V2

@jdimond 

In this PR
1. Removed the dependency on `com.firebase:firebase-simple-login:*`
2. Updated the dependency on Firebase to `com.firebase:firebase-client-android:1.0.19-SNAPSHOT`
3. Added Twitter OAuth
4. Added Email/Password
5. Replaced all references to `simplelogin` to `login`
sure, i actually added `GoogleOAuthActivity` (albeit unused) to un-clutter the mess, but it seemed a bit hopeless since Facebook was integrated so deeply. I'll take a stab at it again later, but I thought that it may be nice to see each provider by itself so I left it in.