Updates P2_ID for scalariform and scala refactoring

Since the Scala OSGi bundles are used through all projects, there
is no need anymore to add the Scala IDE UID to the scalariform and scala
refactoring P2_ID.

P2_ID are used as ids for the cache system. They contain all dependencies of a project, to make sure to not use a cached build if something has changed.
I'm not quite sure how good it was working right now, as the Scala IDE UID
was not defined at this point.