Merge branch 'knepley/upgrade-petsc-interface' of github.com:geodynamics/pylith into knepley/upgrade-petsc-interface

* 'knepley/upgrade-petsc-interface' of github.com:geodynamics/pylith:
  Faults: Turn off Line2 test for cohesive fault right now
  Turn off some debugging
  BC: Only allow vertices in BC points
  Mesh: Hardwire mesh interpolation
More work on reordering unit tests.
Add some output to indicate forced failure of test.