Add Travis testing

[decentral1se]

I'd be happy to submit a pull request with the initial .travis.yml file.

This would potentially close #3, #23 and #55 when we create a travis run that tests across multiple python/django versions. It's not much work and the gains are big.

Could you set up travis for this repository?

[decentral1se]

Oh, there aren't any tests.

Well, it could simply install the package for now ...