Set up continuous integration testing

[dwysocki]

Currently, we have no automated methods for testing that our commits don't break anything. We simply rely on whatever test cases we think to run, and check that nothing broke before pushing changes to GitHub.

Tools like Travis CI, and other continuous integration tools, allow us to automate that process, and prevent us from merging commits which break our code.

In order to add CI to our workflow, there will be some amount of initial setup. Aside from configuring the tool, we will also need to create a number of test cases. Once we have those test cases in place, it will become much safer to develop at a fast pace, and only when we make significant changes will we need to edit our test code.