Adding compositional adaptive module with mpfa on hanging nodes (as announced in last Dumux meeting). A test and reference is also provided.
The module is stable, but doxygen docu is still needing some improvement.

git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@9145 2fb0f335-1f38-0410-981e-8018bf24f1b0