Simplify QuitGanetiException instantiation

Rather than packing all the arguments in a tuple, let's pass them
plainly. The superclass won't complain.

Reviewed-by: iustinp

lib/errors.py

@@ -224,15 +224,15 @@ class QuitGanetiException(Exception):
 
   This is not necessarily an error (and thus not a subclass of GenericError),
   but it's an exceptional circumstance and it is thus treated. This instance
-  should be instantiated with a tuple of two values. The first value will
-  specify whether an error should returned to the caller, and the second one
-  will be the returned result (either as an error or as a normal result).
+  should be instantiated with two values. The first one will specify whether an
+  error should returned to the caller, and the second one will be the returned
+  result (either as an error or as a normal result).
 
   Examples:
     # Return a result of "True" to the caller, but quit ganeti afterwards
-    raise QuitGanetiException((False, True))
+    raise QuitGanetiException(False, True)
     # Send an error to the caller, and quit ganeti
-    raise QuitGanetiException((True, "Fatal safety violation, shutting down"))
+    raise QuitGanetiException(True, "Fatal safety violation, shutting down")
 
   """