Ref #179, setup.py should install wxpython

This commit does not really address #179,  however installation from source fails explicitly. And 'explicit' is better than a 'silent' installation.

Feel free to decline. Tested on Ubuntu12.04 x86_64.

wxPython doesn't support setup.py:
http://superuser.com/a/196258/292783
http://wxpython.org/builddoc.php