Regression gold standard updates

For dirichlet_fem and penalty_poiseuille_stab. dirichlet_fem is updated
because of a bug fix on the libMesh side and penalty_poiseuille_stab
is updated based on fixes in #157.
Merge pull request #162 from pbauman/regression_updates

Regression gold standard updates
First round of modifications for spatiallyvarying viscosity
Errors fixed for stokes
Almost there for the constant case
ConstantViscosity should now be working
MU templating compiles but failing test_stokes_poiseuille_flow
Passed regression tests (apart from a couple related to new libMesh changes and a broken regression)
Passing context changes: stokes
Merge pull request #163 from vikramvgarg/spatiallyvaryingviscosity

IncompressibleNavierStokesBase Viscosity template parameter
Passing regressions tests (except the two that are not an issue right now)
First changes for adding spatially varying viscosity function
Parsed Viscosity class declaration and definition
Getting there with the parsed spatiallyvarying viscosity
Added ParsedViscosity capability
Removed some reduntant functions in parsed_viscosity
Test 1 for parsed viscosity
New test successful, ready for merge with master and variable viscosity tests
PR errors found y Roy
Passing context changes: stokes