Test Travis-CI with MySQL + MariaDB + PostgreSQL

[dennissiemensma]

Follow-up for #48, also test with MySQL & PostgreSQL: https://docs.travis-ci.com/user/database-setup/

./manage.py test --settings=dsmrreader.config.test_postgresql -v2 --noinput

./manage.py test --settings=dsmrreader.config.test_mysql -v2 --noinput

[dennissiemensma]

I need this shortly, as I once again forgot to check mysql & postgresql after merging. They now break on a test due to inline management command flush to reset the database. I need to see it fails in the branch.

[dennissiemensma]

Somehow #62 was fixed as well.

[dennissiemensma]

Nice, I finally got all three database engines covered by Travis!

https://travis-ci.org/dennissiemensma/dsmr-reader/builds/114641595

 Python: 3.3 DB=sqlite DJANGO_SETTINGS_MODULE='dsmrreader.config.travis.sqlite'
 Python: 3.3 DB=mysql DJANGO_SETTINGS_MODULE='dsmrreader.config.travis.mysql'
 Python: 3.3 DB=postgresql DJANGO_SETTINGS_MODULE='dsmrreader.config.travis.postgresql'

 Python: 3.4 DB=sqlite DJANGO_SETTINGS_MODULE='dsmrreader.config.travis.sqlite'
 Python: 3.4 DB=mysql DJANGO_SETTINGS_MODULE='dsmrreader.config.travis.mysql'
 Python: 3.4 DB=postgresql DJANGO_SETTINGS_MODULE='dsmrreader.config.travis.postgresql'

Now I really have to triple check tests when I merge something to master ;-)