[server/kit] added OpenCensus Stackdriver exporters and GCP error reporting for GKE, GCE & AWS environments

Initialize opencensus for GKE (#176)

* Initialize opencensus for GKE

* update readme

* Generalize initialization of sd exporter

* fix sdExporterOptions

* do not initilize SD exporters and error reporting unless we are in the cloud or set proper environment variables

* Update doc

* address comments

* remove redundant if