ENH: move tests/* under cortex/tests/test_*

This should
1. simplify discovery of tests with common testing frameworks suchas nosetests
2. allow users to test cortex "as installed" since tests will be shipped
   along now

also setup.py got executable permission since it should have it anyways ;-)
Merge pull request #41 from neurodebian/enh/move_tests_under_pycortex

ENH: move tests/* under cortex/tests/test_*