Moving test requirements into its own area.  Worked on Fedora19, python 2.7.  #51
Not going to bother with a test_requires section.  Closes #51.

Numpy causes trouble on the mac with test_requires.  Anyway, the only
real hard requirement is "mock" with 2.6 and 2.7, and that's hardly
worth the extra trouble.  matplotlib and pillow are optional requirements.
Simplified test requirements, dropping scikit-image and freeimage.

closes #51
Merge branch 'issue51' into devel