WIP: Otter / open tracing support
Adding open tracing support, work in progress.
So far this adds the following query parameters:
&trace_idgenerates a new trace for the call
&trace_id=<integer>uses an provided trace id
&parent_id=<integer>uses a given parent ID.
- Deal with filters (depends on filter changes for otters?)
- Return a trace_id as part of a header field if one was used.