Introduce Guru Meditation Reports into Nova

This commit integrates functionality from the
`openstack.common.report` module into Nova.
This enables Nova services to receive SIGUSR1
and print a Guru Meditation Report to stderr.
The required modules were added to
'openstack-common.conf' as well.

Change-Id: I224a426dad084f0e738069207ffbffe7f7935a17
Implements: blueprint guru-meditation-report
Merge "Introduce Guru Meditation Reports into Nova"