(WIP) Removed uberfire-security-server and cleaned up the resulting compile issues.

Right now, all non-test code compiles, but the tests don't compile and the showcase app doesn't deploy.
Further commits will clean these loose ends up.
All security filter tests that still make sense are passing!
Our customizable auth filter is now part of PicketLink 2.6.0-SNAPSHOT
Added final auth scheme behaviours required by the tutorial app
Now using Errai's AuthenticationService to obtain current user
Getting ServletContext from Errai now, since UberFireServlet is gone
The SecurityExtension is no longer a thing
Updated showcase for new server-side security setup
Fixed JBossAS and Tomcat war setups (API jars were causing deployment issues)
Ignore generated file