reflect the change from "mediaanalytics" to "mediametrics"

Also incorporates a broader access to the service -- e.g. anyone.
This reflects that a number of metrics submissions come from application
space and not only from our controlled, trusted media related processes.
The metrics service (in another commit) checks on the source of any
incoming metrics data and limits what is allowed from unprivileged
clients.

Bug: 34615027
Test: clean build, service running and accessible
Change-Id: I657c343ea1faed536c3ee1940f1e7a178e813a42