Allow to specify service name and endpoint IP respectively for zipkin tracing (#1353)
Allow to specify service name and endpoint IP respectively for zipkin tracing (#1353)

* Allow to specify service name and hostPort for zipkin tracing

This patch allows to specify service name and hostPort for zipkin tracing.

Currently the serviceName(display in the console) and
hostPort(endpoint) must be same name.
To make matters worse, the hostPort only supports `80` port.

This patch allows to specify both serviceName and hostPort. Also,
hostPort can be `IP:PORT` format for port customization.

* Fix review comments

* Remove port
knative/pkg,knative/pkg