Weak-plane shear plasticity added.  Fixes #3535

A number of tests have been added that demonstrate correctness
for small and large deformations.

Fairly comprehensive doco can be found on the mooseframework.org wiki.

Please don't be too harsh in judging the coding quality.  I have
great plans for these plasticity Material classes, and this present
class will probably change greatly over the next few weeks, but
since this works as planned i'd like it to be merged now, so that
people can play and comment on things.  Otherwise the changes in
"a few weeks" will be far too big for one PR.
Tension release #3548
Adding MeshChangedInterface so any object can be notified when the mesh is changed refs #3549
Merge pull request #3550 from jasondhales/tension_3548

Tension release #3548
Merge pull request #3551 from friedmud/mesh_changed_interface_3549

Adding MeshChangedInterface
Fixed #3514.  Added eigenvalue computation to RankTwoTensor, also
derivatives of the invariants, which will be needed for plasticity
models.

I think everything is fully tested using CPPUNIT

Thanks @jwpeterson for all your comments
RichardsBorehole: added ability to specify one point only, along with a length and direction.  Tested.  Fixes #3561
Merge pull request #3562 from WilkAndy/one_dirac_3561

RichardsBorehole: added ability to specify one point only, along with a ...
Merge pull request #3541 from WilkAndy/weak_plane_mc_3535

Weak-plane shear plasticity added.  Fixes #3535
Merge pull request #3515 from WilkAndy/dsyev_3514

Fixed #3514.  Added eigenvalue computation to RankTwoTensor.  Untested