Use setuptools instead of distribute.

Distribute does not support "install_requires":
<http://stackoverflow.com/a/10686196/113527>.

Since Setuptools and Distribute have merged (see
<http://pythonhosted.org/setuptools/merge-faq.html>), this should not
cause any loss of functionality. Your virtualenvs may need to be
updated, though.
Slightly better Python 3 compatibility.

  * Import parse_qs correctly.
  * Fix syntax error with exceptions.
  * Update access token test to work with both Python 2 and Python 3.
Update classifiers & Travis config w/ Python 3.3.