Import propertysystem

this imports the (currently eWoms specific) property system, but renamed to 'OPM'. It needs the files 'classname.hh' and 'exceptions.hh' from dune-common. Since I am pretty sure that adding a dune requisite is not well liked, I forked these files.

this PR is a continuatuation of opm/opm-core#332 , which I accidentially closed in my stupidity...