Merge branch 'knepley/upgrade-petsc-3.5'

* knepley/upgrade-petsc-3.5:
  Another update for PETSc 3.5.1 in libtests.
Small fix for running tests with latest automake.
Merge branch 'knepley/upgrade-petsc-3.5'

* knepley/upgrade-petsc-3.5:
  Configure: Upgrade to PETSc 3.5.2
Modified manual, code, and unit tests for error in Drucker-Prager
elastoplasticity. We were missing the initial pressure term. I haven't
tested yet.
Minor fix in Drucker-Prager equations (does not affect results).
Merge branch 'willic3/fix-plasticity' into maint