Placement Policy for RHEV VMs.

Conflicts:
	utils/mgmt_system.py
Check for placement policy affinity

(cherry picked from commit b6e3bbe8920cace995e67abfc023dd1ccc6ecce6)
Check if key exists in kwargs.

(cherry picked from commit a3562677676fa9ab24df6014432a24876ba8ad8c)
Merge pull request #659 from akrzos/perf_rhev_placement_policy

Perf rhev placement policy