Created so-called dumb deactivation scheme that can act as a last-resort to finding the active constraints.  Added test using a typical multi-plasticity model used in rock mechanics.  Fixes #4043
Minor tweak to logic for acceptStep() call closes #4041

I took a fresh look at this and realized that _picard_converged
would never be true here, so removed it from conditional check.
Merge pull request #4045 from bwspenc/picard_sync

Minor change to picard iteration logic
Merge pull request #4044 from WilkAndy/dumb_4043

Created so-called dumb deactivation scheme that can act as a last-resort...
Merge pull request #4046 from dschwen/expb_4040

Add comparison operators to ExpressionBuilder
Fix clang compiler error
refs #4044
Add plog function (#4047)
Introduce substitution functors (#4047)