Add user id to visualizations

Fix user authentication decoding

Remove log file in development mode

Change development to verbose output

Only temporary. Will be added again later on.

Removed adminLevel from users

Add missing simulator attribute in plot model

Rename server.js to app.js.
Add 404 and error handling middleware.

Post routes create needed relationships when creating new entries.
The associated entires are deleted on deleting an entry (e.g. deleting a project
leads to deleting all visualizations and plots belonging to this project.

Add relationship from visualization to project.
Add plot-type attribute.

Change response on delete routes.

Add cors package.
Add /users/me route to identify from auth token.

Add UML class and use-case diagram (StarUML application).
Add admin user from config if no admin user found.