Merged the MultiPhysicsCrystalPlasticity model back into the CrystalPlasticity model.

The MultiPhysicsCrystalPlasticity model was intended for model development for Jay's
LDRD.  Following a discussion between Reese, Jay, Dave, and Hojun this morning, the
LDRD will instead just build directly upon the CrystalPlasticity model.

The original CrystalPlasticity examples have been removed and replaced by new versions
that use exodiff.  Subsequent commits will straighten out the naming of these tests
to remove the MultiPhysics moniker.  I would have included this change here, but I don't
trust my git skills enough to remove the CrystalPlastity examples directory and then
rename an existing examples directory CrystalPlasticity.