Testing PyGObject Applications with Travis-CI

This runs py.test, pyflakes and pep8 on the file test.py on travis-ci. This runs on Ubuntu 14.04, so the used GTK+/PyGObject is rather old.

For newer GTK+/PyGObject have a look at the docker examples:

https://github.com/pygobject/pygobject-travis-ci-docker-examples

https://pygobject.readthedocs.io/