Fix _sync_power_states to obtain correct 'state'.

Update the compute manager to obtain state from the get_info
dict correctly.

Fixes 'dict' object has no attribute 'state' error that occur
when syncing power states.

Fixes LP Bug #934276.

Change-Id: I3e3602018f4c38f78b48186bfca78eda362a9e54

nova/compute/manager.py

@@ -2244,7 +2244,7 @@ def _sync_power_states(self, context):
             db_power_state = db_instance['power_state']
             try:
                 vm_instance = self.driver.get_info(db_instance)
-                vm_power_state = vm_instance.state
+                vm_power_state = vm_instance['state']
             except exception.InstanceNotFound:
                 LOG.warn(_("Instance found in database but not known by "
                            "hypervisor. Setting power state to NOSTATE"),