Merge with branch develop

Release version

cps/server.py

@@ -156,7 +156,7 @@ class WebServer(object):
                                  max_buffer_size=209700000,
                                  ssl_options=self.ssl_args)
         http_server.listen(self.listen_port, self.listen_address)
-        self.wsgiserver = IOLoop.instance()
+        self.wsgiserver = IOLoop.current()
         self.wsgiserver.start()
         # wait for stop signal
         self.wsgiserver.close(True)
@@ -177,6 +177,8 @@ class WebServer(object):
 
         if not self.restart:
             log.info("Performing shutdown of Calibre-Web")
+            # prevent irritiating log of pending tasks message from asyncio
+            logger.get('asyncio').setLevel(logger.logging.CRITICAL)
             return True
 
         log.info("Performing restart of Calibre-Web")
@@ -197,4 +199,4 @@ class WebServer(object):
             if _GEVENT:
                 self.wsgiserver.close()
             else:
-                self.wsgiserver.add_callback(self.wsgiserver.stop)
+                self.wsgiserver.add_callback_from_signal(self.wsgiserver.stop)