Move project to use OpenCensus

[SergeyKanzhelev]

The idea is to replace and port all data collectors to https://github.com/census-instrumentation/opencensus-python

OpenCensus repo will have an exporter that calls into API developed in this repository.

[gugu91]

Hi @SergeyKanzhelev, is there an ETA on this? Also it's listed as help wanted, is this happening in this repo?