Working through converting MueLu examples.  Turned Zoltan2 on in
Trilinos cmake script for Tpetra branch, which is needed for repartitioning.

Right now repartitinoing won't work with MueLu because the coordinates are not
passed properly to MueLu in Piro_NullSpaceUtils.cpp in the piro package of Trilinos.
Capabilities there need to be extended to pass the coordinates to MueLu when selecting
MueLu preconditioner.