Make shapeworks and python module dependencies of their respective tests

[cchriste]

The shapeworks executable and Python module are both tested using system calls to bash and python, respectively.

They aren't necessary as dependencies for the tests themselves, so building/running these tests does not rebuild what is being tested even it was changed.

[akenmorris]

It might be better to restructure the python tests to use an embedded interpreter rather than invoking a new interpreter for each test. Loading the modules alone takes about 5 seconds, so PythonTests takes a considerable amount of time just reloading the interpreter again and again.

This would kill two birds with one stone as the python tests would be part of the executable and automatically be built correctly.