Add self tests; use Odoo official repos

Highlights:
  - The `.travis.yml` is now capable to self test the quality tools.
  - Odoo installation now uses the official Odoo repo and pip installs dependencies.
  - Fixed a couple of issues revealed by the self tests.

Enjoy.
Can you add a large comment stating this travis.yml file should NOT be used in OCA addon repos? That the correct one is in sample_files/.travis.yml