Invalid User Id giving 400

[Hazelfire]

Currently, if the frontend passes an invalid user id (which sometimes happens in production), the backend will return a 500 error. This patches this problem, catching the error and returning it as a 400. I also have an rspec test that checks this.

This pull request does a number of things:

• Creates a docker-compose file configured for both testing and development
• Updates Ruby to 2.7.5
• Adds a manifest file, required by newer versions of sprokets (although, it doesn't really need to do much considering it's a simple API)
• Updates the factories to call their functions using {}, also required in newer versions of dependencies

Rspec does come back clean. And the app seems to work fine.

This fixes the server side problem of getguesstimate/guesstimate-app#1011. I'll see if I can hunt down the client side problem (why the client is sending invalid user ids in the first place)