White space fixes/ relative imports/ fix tests.

These are all the changes necessary to bring the jgoppert github and
python-control github branch in sync. The changes have all been
hand merged. The changes are primarily pep8 white space and other
formatting fixes. There were also some tests fixed.
Modify setup.py to match numpy.
Modify runtests.py to match numpy.
Define __repr__ as __str__ for statesp/ xferfcn.