[TIMOB-15998] implemented support for attributed string on Android

https://jira.appcelerator.org/browse/TIMOB-15998

Implemented support for attributedstring
@salachi Since Chee Kiat created another ticket to handle the iOS parity, could you just write the documentation for Android separately and leave the iOS as it was? 

Chee Kiat will handle the iOS part and fix the documentation to show parity later.