merge from implicit branch: serialize the elements in for cell centered

models, include ccpropertydefaults at the end of ccproperties analogous
to box. Reviewed by gruenich.


git-svn-id: svn://svn.iws.uni-stuttgart.de/DUMUX/dumux/trunk@9874 2fb0f335-1f38-0410-981e-8018bf24f1b0