Set up a proper integration pipeline

[fairingrey]

https://github.com/fairingrey/actix-realworld-example-app/blob/master/.travis.yml is actually pretty scarce at the moment. All it does is run cargo check --verbose on the codebase to see if there are any syntax errors.

The idea later is that we should perform some sort of database dump (probably pg_dump to .sql), see that Travis imports the db into their box, run the backend application on their machine, run tests against it, and then gracefully shutdown after all tests have hopefully passed.