Tpetra: fixing Distributor error with MPICH

Bug#6069.
The distributor class was incorrectly using -1 as the value for
MPI_ANY_SOURCE.  This is implementation dependent.  It happens to work
with OpenMPI.  MPICH2 uses -2, however.   This was causing problems
in initial neighbor discovery, which manifested later in thrown errors
in Directory construction.  Many thanks to Paul Lin and Mark Hoemmen for
suggestions that helped in tracking this down.

Build/Test Cases Summary
Enabled Packages: Tpetra
Enabled all Forward Packages
0) MPI_DEBUG => passed: passed=578,notpassed=0 (39.10 min)
1) SERIAL_RELEASE => passed: passed=506,notpassed=0 (16.37 min)
MueLu: reenable MPICH in nightly tests

switching from OpenMPI.
Tpetra: sparse mat-mat: Fixed build warning (unreachable code).

Build/Test Cases Summary
Enabled Packages: Tpetra
Enabled all Forward Packages
0) MPI_DEBUG => passed: passed=72,notpassed=0 (1.63 min)
1) SERIAL_RELEASE => passed: passed=56,notpassed=0 (0.29 min)
MueLu: fixed CoarseMap unit test

It was not setting the level ID correctly, resulting in some weirdness
due to out of boundary access in CoarseMapFactory.
STK: Adding an argument to turn on/off lower case conversions in STK I/O

This also allows spaces in field names. For instance if the parameter
is set to true then

   "Lattice Temperature" => "lattice_temperature"

if the parameter is set to false then

   "Lattice Temperature" => "Lattice Temperature"
Panzer: Adding option to force exodus fields to lower-case

The lower-case was the default. The new default is to leave the
fields alone (and even allows spaces in the field names). The old
capability can still be turned on by specifying "User Lower Case"
in the input deck. Note that the previous change to STK was required
to achieve this.
Panzer: Fixing issue with stokhos build

This followed from the removal of a bunch of response library
code. Its not used anymore anyway.
ML: Fixing null pointer read in aggregation

Build/Test Cases Summary
Enabled Packages: ML
0) MPI_DEBUG => passed: passed=33,notpassed=0 (15.98 min)
1) SERIAL_RELEASE => passed: passed=32,notpassed=0 (3.27 min)
Adding sideset information to RectGrid.m.

Other minor changes.
MueLu: putting mpi version in dashboard test label