POC Add basic tracing capabilities to Nuxeo

Using opencensus we need to instrument our code to add annotation and propagate the trace context.

• propagate from web request: taking in account taceConfig or B3 HTTP headers
• propagate from work manage
• propagate from stream
• propagate from quartz
• basic instrumentation of Nuxeo service:
• event service: annotate fired events
• core session: trace nxql query, session save ...