#177693: Code completion in .erb does not work properly

Please review the fix for 
https://netbeans.org/bugzilla/show_bug.cgi?id=177693

Description: Code completion does not work properly in ERB files

Problem: The main cause was an earlier change made in how the code 
completer retrieves the token hierarchy for the file being edited. In 
addition a part of the problem was that all class methods whose return 
types the IDE can't infer were considered to return classes (hence 
instance methods were not shown in the CC dialog), whereas in reality 
they typically return instances.

Fix: Reverted the change wrt. the token hierarchy retrieval and changed 
the assumption wrt. return types of class methods.

Verified by Tomas Musil.

Thanks
Erno