dom0/qmemman: distribute memory freed by deleted domain

Also wait a moment after domain list change for domain cleanup. Even if this
time is not sufficient, memory will be balanced when some domain need it.

dom0/qmemman/qmemman.py

@@ -28,6 +28,7 @@ class SystemState:
 
     def del_domain(self, id):
         self.domdict.pop(id)
+        self.do_balance()
 
     def get_free_xen_memory(self):
         return self.xc.physinfo()['free_memory']*1024

dom0/qmemman/qmemman_server.py

@@ -33,6 +33,7 @@ class XS_Watcher:
         self.watch_token_dict = {}
 
     def domain_list_changed(self, param):
+        time.sleep(0.05)
         curr = self.handle.ls('', '/local/domain')
         if curr == None:
             return