Justin's update to the Geomcomp + tests

From Justin's Pull request on my branch:

Added 5 tests, all of which fail from what I think are bugs in the derivative code (or the GeomCompCode).

Two new tests are in test_derivatives_objects
Two are in Test_derivatives_geomcomp

Two of the tests are essentially replicated from objects to geomcomp tests. So fixing these bugs will fix all four tests.

I think have a potential "fix" for test_geom_provide_deriv_check_fd_tail: 
On line 702 of derivatives.py replace 
width = flattened_size(srcs[0], val)

with 
width = flattened_size(srcs[0], val,self.scope)

The issues seems to be related with the scope of the thing in the model slot not being set properly. self.scope seems to help that. This only exposes the underlying bug though, which also shows up in the companion test from test_derivatives_objects.

There is one last issue with the geomcomp test... the derivatives don't match the fd. This is what led me to make the ProvideJ version of the tail comp in the first place (which exposed another bug). I can't find my mistake in the applyder and and applyderT methods though.