Server needs tests

[lukel97]

At the moment the server component has no tests at all, so it would be a good idea to add some simple smoke tests to begin with. We should use Jest but I'm not sure if it will clash with the version of Jest that create-react-app installs in the client. (It would probably be a good idea to begin to completely separate it out from the client so that it's package.json is located within the server directory, and having another package.json at the root combining the two)