Simplify tracing

[Daníel Sigurgeirsson]

Tracing is currently enabled in the Web API, but is too detailed. The real actions simply get lost in the noise in the trace file.

We need a simple trace, for every request to the API:

• what URL is being requested
• the request headers
• what user is authenticated (if any)
• the current date

and possibly something more. Each request should be a single line in the "log file", which could be a database table as well.

[Daníel Sigurgeirsson]

Done (although not on master yet)