* Update grafana install instructions.
This PR updates text around accessing the Istio dashboard configured
in the grafana image. It adds a default screenshot of an empty dashboard
and suggests port-forward as the simplest way to access the dashboard.
Fixes#49.
* Address review comments
This PR simplifies some of the task by:
- eliminating non-essential istioctl mixer validation step (now handled in reference docs)
- eliminating the new request_size metric from the rule, as envoy doesn't currently seem to produce non-zero values for request.size
- using grafana for metrics validation (instead of port-forwarding and searching through /metrics)
Douglas Reid