core: change policy unit names

Rename "PowerSaving" to "OptimalForPowerSaving"
Rename "EvenDistribution" to "OptimalForEvenDistribution"

Change-Id: I5f8b2fc699eb70c39ded790ed9c13ce6b456046c
Bug-Url: https://bugzilla.redhat.com/999539
Signed-off-by: Noam Slomianko <nslomian@redhat.com>