Changes: upgrade to bootstrap3, fix of some runtime errors

Hi there!
It is a great job what you have done in 'play-authenticate'!

I'm a newbie in Play, and of course in 'Play-Authenticate'. Right now, I'm developing a new system, and I decided to do it with Play secured with play-authenticate.

This module breaks in some places at soon as I tested. So, I decided to fix those bugs, and send them to you. Also, I decided to upgrade it to bootstrap3. 

About the last point, (bootstrap3), I replace all @main for @main3, and it seems to invalidate css styles that blocks bootstrap3. This sends a message to log, but it does not break the system.

I hope, all these code may be useful to you for enrich Play-Authenticate!

Regards!