SideSetsAroundSubdomain runs with ParallelMesh.

The algorithm doesn't use flood().

Refs #2129.
rz cylindrical gap conductance capability comments incorporated per #3142
Merge pull request #3146 from novasr/feature_3142

rz cylindrical gap conductance capability per #3142
Merge commit '93faeb57a41cda080b113fe90a3eb61654139562'