Fix history saving from server disconnect

When server disconnect cli is hardly killed and history is not saved.
Now we just warn about disconnection

cccli/handler.py

@@ -22,7 +22,7 @@ class CliHandler(RpcHandler):
     @pure
     def quit(self, rpc=None):
         '''Call back function on server disconnect'''
-        Printer().fatal("Disconnected from server!")
+        Printer().warn("Disconnected from server!")
 
     @pure
     def get_tags(self, complete=None, partial=None):