MueLu: RAP,RebalanceTransfer: cleaned up implicit transpose interface

- RAP: moved implicitTranspose_ to parameter list
- RebalanceTransfer: added implicit transpose option
- Hierarchy: added GetDefaultImplicitTranspose()
MueLu: new interface parameter for implicit transpose

"transpose: use implicit" enables construction of hierarchies without
explicitly constructing restrictor. Should work in both simple and
rebalanced mode.
MueLu: fixed misprint in the API guide
MueLu: interface: added a few implicit transpose tests
TrilinosCouplings/FENL:  Added embedded sampling-based UQ.

This commit makes TrilinosCouplings optionally dependent on Stokhos, and
adds a preliminary implementation of embedded sampling-based UQ in the
FENL example.  This required templating some of the code on the scalar
type, and adding a new executable that does a UQ loop (controlled from
the command line).  To eliminate code duplication between the two
executables, I refactored much of the setup code into helper functions.
I also added a response function so that it's statistics could be
printed to the output.  Currently it is the two-norm of the discrete
solution vector, but soon will be refactored to a proper two-norm of the
solution.
Stokhos:  Fix volatile for Sacado::MP::Vector +=,-=,*=,/= operators.

I was dropping the volatile qualifier in the overloads that take
volatile expressions.  These overloads are necessary since I don't
provide overloads explicitly for Sacado::MP::Vector arguments, which can
be volatile, even though expressions never are.
Panzer: Removing incorrect assertion
TrilinosCoupling/FENL:  Add Belos/MueLu solve.

Added Belos and MueLu to FENL.  This can be used instead of the native
CG solver that was already there.  Add "belos" to the command line to
get the Belos solver, and "muelu" to turn on MueLu preconditioning.
Currently it is hard-coded to read muelu.xml for the MueLu settings.
Note, there is currently a problem with the RAP in MueLu for
KokkosRefactor that this xml file exposes.

Thanks to Jonathan for most of this work.
Tpetra:  Fix setting of rowPtrs_ in the local CRS graph constructor.

The Tpetra::CrsGraph constructor that takes a local CRS graph had the
setting of rowPtrs_ commented out.  This was causing an exception to be
thrown by Ifpack2::Chebyshev in getRowInfo().  I "fixed" this by adding
a const_cast so that rowPtrs_ could be set.  This is just a temporary
workaround.
Initial implementation of a preconditioner for Maxwell's equations,
using the 2x2 block reformulated approach.
Merge branch 'master' of software.sandia.gov:/space/git/Trilinos
Stokhos:  Fix some unused typedef warnings in non-debug builds.
Merge branch 'master' of software.sandia.gov:/space/git/Trilinos
gtest: suppress warnings about variadic macros when building with gcc
KokkosExamples: fix warning about a non-void function without a return type
Kokkos: fixed some bugs encountered when compiling with gcc-4.7.2 on bgq