Removed some more RCE graph references

Former-commit-id: ffac4bfc46014b2c43b9e6b353df069af200df6d

kadmos/graph/__init__.py

 from graph_kadmos import KadmosGraph
 from graph_kadmos import load
 from graph_data import RepositoryConnectivityGraph, FundamentalProblemGraph, MdaoDataGraph
-from graph_process import MdaoProcessGraph, RceGraph
+from graph_process import MdaoProcessGraph

kadmos/graph/mixin_vispack.py

@@ -158,12 +158,11 @@ class VistomsMixin(object):
         """Function to check the inputs for the VISTOMS instance functions."""
 
         from graph_kadmos import KadmosGraph
-        from graph_process import MdaoProcessGraph, RceGraph
+        from graph_process import MdaoProcessGraph
         assert isinstance(self, KadmosGraph)
         if mpg:
             assert isinstance(mpg, MdaoProcessGraph)
         assert not isinstance(self, MdaoProcessGraph)
-        assert not isinstance(self, RceGraph)
         assert isinstance(function_order, list) or function_order is None
         assert isinstance(vistoms_version, basestring) or vistoms_version is None
         if reference_file is not None: