Hardening added to WeakPlaneTensile.

Three nice tests added.

Also, FiniteStrainPlasticBase now provides a Material which is
the number of Newton-Raphson iterations used.  This is useful for
debugging, but also i think it'll be useful in the future when
we have to apply the strain increment in small amounts in order
to return to the yield surface for very nonlinear models.

Fixes #3625
Automatically set pc_hypre_boomeramg_strong_threshold to 0.7 for 3D meshes
closes #3245
Override the automatic adjustment of the strong threshold few a few sensitive tests
Merge pull request #3628 from WilkAndy/wpt_hard_3625

Hardening added to WeakPlaneTensile.
Merge commit '83a7937f1e4a2852f6036de482b973d294608a0d'
Merge pull request #3630 from permcody/hypre_threshold_3245

Automatically set pc_hypre_boomeramg_strong_threshold to 0.7 for 3D mesh...
Merge commit '80480a7cfe3cfc6de7d17ca57d2a46be27619879'
Fix a bad optimization refs #3586
Merge commit '7169bf999f7c855e53d9abc43019546acf649f5f'