exporter/zipkin: if localEndpoint is not specified, resolve it from system

[odeke-em]

Currently when creating the Zipkin exporter, if no local_endpoint is specified in the configuration file, we use a phoney local endpoint URL

opencensus-service/exporter/exporterparser/zipkin.go

Lines 99 to 102 in 77741c8

	localEndpointURI := "192.168.1.5:5454"
	if zc.LocalEndpointURI != "" {
	localEndpointURI = zc.LocalEndpointURI
	}

and the origins of it are I believe from copy and paste through Zipkin documents.

Because deploying many agents will require us to provide accurate information about origins of content, it is essential that we use the locally resolved address of the source as local_endpoint if none is provided.