MueLu: Adding more data writing capabilities

Matrices "A", "P", and "R" can now be written via XML specification.
The numbers in brackets specify the levels you want written.  Invalid level numbers are ignored.

  <ParameterList name="Hierarchy">

    <Parameter name="numDesiredLevel" type="int"      value="10"/>
    <Parameter name="maxCoarseSize"   type="int"      value="1000"/>
    <Parameter name="verbosity"       type="string"   value="High"/>

    <ParameterList name="DataToWrite">
       <Parameter name="Matrices"          type="string"   value="{0,1}"/>
       <Parameter name="Prolongators"      type="string"   value="{1,2}"/>
       <Parameter name="Restrictors"       type="string"   value="{1,2}"/>
    </ParameterList>

    ...
  </ParameterList>

Maps are always written in a separate file along with the vector or matrix.

Coordinates are written by specifying them in the coordinate transfer factory definition.
This is because they are not currently saved on the level after construction of the hierarchy is finished:

    <ParameterList name="myTransferCoordinatesFact">
      <Parameter name="factory"                             type="string" value="CoordinatesTransferFactory"/>
      <Parameter name="write start"                         type="int"    value="0"/>
      <Parameter name="write end"                           type="int"    value="3"/>
    </ParameterList>

This is annoying because coordinates are treated differently than other data, but it works.
MueLu: update xml deck to show how to write data

Build/Test Cases Summary
Enabled Packages: MueLu
Disabled Packages: MOOCHO
Enabled all Forward Packages
0) MPI_DEBUG => Skipped configure, build, test due to no enabled packages! => Does not affect push readiness! (-1.00 min)
1) SERIAL_RELEASE => Skipped configure, build, test due to no enabled packages! => Does not affect push readiness! (-1.00 min)
2) MPI_SS_DEBUG => passed: passed=86,notpassed=0 (10.68 min)
Other local commits for this build/test group: 0dc0f1f
Zoltan2: MJ minor bug fix.
Zoltan2: MJ added less costly migration when nprocs < num_parts
Zoltan2 MJ added second type of processor assignment for migration.
Zoltan2 MJ commented out the migration code.
Merge branch 'master' of software:/space/git/Trilinos
Black box Shifted Laplacian-preconditioned solver for Helmholtz. Stuck it in muelu/adapters momentarily.

Build/Test Cases Summary
Enabled Packages: MueLu
Enabled all Forward Packages
0) MPI_DEBUG => Skipped configure, build, test due to no enabled packages! => Does not affect push readiness! (-1.00 min)
1) SERIAL_RELEASE => Skipped configure, build, test due to no enabled packages! => Does not affect push readiness! (-1.00 min)
2) MPI_DEBUG_SS => passed: passed=86,notpassed=0 (47.19 min)
MueLu: touched CMakeLists.txt to trigger rebuilds
Galeri: fix for calculation of the number of subdomains

The bug was introduced in commit ce1e065c07