Fix added_sides writing of non-initial variables
Fix added_sides writing of non-initial variables

This was an embarrassing bug.

jwpeterson/libmesh,dschwen/libmesh,libMesh/libmesh,libMesh/libmesh,jwpeterson/libmesh,libMesh/libmesh,jwpeterson/libmesh,dschwen/libmesh,libMesh/libmesh,jwpeterson/libmesh,jwpeterson/libmesh,libMesh/libmesh,jwpeterson/libmesh,libMesh/libmesh,jwpeterson/libmesh,dschwen/libmesh,dschwen/libmesh,jwpeterson/libmesh,dschwen/libmesh,dschwen/libmesh,dschwen/libmesh,dschwen/libmesh,libMesh/libmesh,libMesh/libmesh