Sample notifications

Generates a new class of "SAMPLE" notifications.
These samples come from host, ram, cpu, volume and
network information already collected periodically
from the hypervisor.

Sample notifications have a SAMPLE priority and event
names like "sample.cpu", "sample.ram", "sample.volume",
etc.

Normally this data would flood the queuing system, but
with the new routing notifier we are able to process
these events in a more efficient manner (or ignore them
completely)