Network: process metering reports from Neutron

blueprint https://blueprints.launchpad.net/ceilometer/+spec/ceilometer-quantum-bw-metering

Change-Id: Idbcc5843e1840ff2659a58d991f4256f56c93a4d
Fixes service startup issue on Windows

A recent addition in Oslo to support SIGHUP created a blocking issue
on Windows due to missing signal.SIGHUP support.

Fixes bug: #1217043

Change-Id: If530cdf8609655ef55aabbad95a2ec8b44ed8679
Reject duplicate events

When ack_on_error=False, there is a possibility that we
could receieve the same message more than once. Reject those events.

Change-Id: I3814a4222298d2fbc56a25e6e4540d01066ee42f
Merge "Network: process metering reports from Neutron"
Merge "Fixes service startup issue on Windows"