Implements filters and schedules in nova.cfg

Adding filters and scheduling parameters to nova.cfg for better to reach
more smooth VM distribution across non-homogeneous compute nodes.

Change-Id: I59a49c613da29eda04eec7dfe911d8fc31380a33
Implements: blueprint scheduler-config-improvements
Closes-Bug: 1300027
Merge "Implements filters and schedules in nova.cfg"