Update for compatibility with current libMesh
Refactor VelocityPenalty, add stabilization

So it turns out that you *can't* always get away with an
residual-inconsistent stabilization method.  Let's start to work on
fixing that.
Add VelocityPenaltyAdjointStabilization test
Fixes for Jacobian errors

We still seem to be about 0.1% off...
Numerical Jacobians for penalty_poiseuille_stab

We'll use this until the analytic Jacobians' error is found.
Add penalty_poiseuille_stab regression values