Set up continuous integration

[Ameobea]

This project could really benefit from some kind of CI that automatically builds the platform in its entirety and runs the full battery of tests. This will require a significant amount of effort but will probably be worth it in the long run.

The first step should be to get all of the tests to pass successfully. Tests involving functionality that no longer exists or must be changed significantly should be removed or disabled until such a time as they can be re-implemented correctly.

Ideally, an automatic deployment system such as now.sh would be set up as well with a full demo version of the platform, but this isn't necessarily in the scope of this issue.