This supplements the release process. We inject Github metadata into two version.json files; the 'version' value will depend on the type of event, for release tag events it should be the same as the release tag (i.e. the app version). This should make version information available to the /config endpoint on any push, and the frontend should display the backend version. (For extra safety we will also want to get the frontend version and display that, but this commit only supplies the barest necessities.)