Added v1 docs
Completed porting the simple login v1.x.x docs
Added link to 1.x.x documentation in main README
Fixed broken links to API reference
Added anonymous auth and fixed custom auth docs
Minor docs fixes
Added deprecation warning to main README
Changed iOS -> Android in docs header
Added login example to Twitter doc
Merge pull request #5 from firebase/jw-v1-docs

Added docs for Android Simple Login v1