• Fix Is this a library or an application? #60: For the time being, it's an application... but we want to be sure not to get boxed in by overly strict version requirements.

This is checking two slightly different things:

• Can we run the end-to-end test with only a couple extra packages besides what a user would get when they install this package? We want to be sure that we aren't relying on dev dependencies in the production code by mistake.
• Can we run the end-to-end test with unpinned dependencies? We want to know if newer versions have introduced breaking changes. (We'll keep the pinned dependencies, too, so if something does go wrong with the unpinned deps, we know who is to blame.)