Central logging of all API calls

[majst01]

To be able to see what happened on every entity by whom we must log every api call.

This can be done with a filter on the api endpoint, examples can be seen here:

https://github.com/emicklei/go-restful/blob/master/examples/restful-filters.go

question arises if we should do that per webservice e.g. /machine and /network to be able to decode the payloads more easily, or once from / and have more work to do to decode the payload.

[majst01]

duplicate of #64

[majst01]

done with https://github.com/metal-stack/metal-api/pull/372