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

https://jira.appcelerator.org/browse/TIMOB-15998

Implemented support for attributedstring
For iOS, it is still type "Titanium.UI.iOS.AttributedString". Until iOS changes this, perhaps the document should list iOS as Titanium.UI.iOS.AttributedString and Android as Titanium.UI.AttributedString.