Add columns Tag

[beikov]

Add a columns Tag, that is already available in primefaces, that should act like a NamingContainer.

[beikov]

Adapted primefaces code, now it has to be changed to act as a NamingContainer

[beikov]

We do already have somekind of an implementation of this, but this is currently just a quick and dirty solution that works for some usecases. We need some integration tests for this before we can really start to implement this. Also the UIData and DataTable implementations would have to be adapted to be not only restricted to rows.

This is a feature that was requested for a long time within primefaces community, but still there is no implementation. We want to provide it as soon as possible, but since the current solution for curecomp fits their needs, there is no need to rush.