Merge in parts of the Py3.3 http.cookielib module

* Keep some old Py2 module imports, especially the urllib submodules which are
* not yet folded into the new Py3 stdlib structure in
* future/standard_library/backports.
Fold in cleanups to test_httplib from Py3.3
Declutter test output
Try installing Python test Ubuntu packages on travis-ci

* This is needed for importing test.string_tests and test.buffer_tests on Py3.