Set up testing for components

[Carifio24]

This PR addresses #3 by adding a basic "test app" where we can use the URL hash to swap out which component is being displayed. For passing in props, we can pass in a query parameter that's a base64 encoding of the props.

This doesn't address every possible thing that we would want to test, but it's a good place to start. This is still a WIP as I still need to actually set up some tests using this setup.

[Carifio24]

So my initial approach had been to set up a little testing app to do this sort of thing. That might still be useful, but it seems that Nightwatch now allows for component testing, so I'm going to investigate that as well.