Cancel all requests during dealloc.

Examples/RKCatalog/Examples/RKRequestQueueExample/RKRequestQueueExample.m

@@ -31,6 +31,7 @@
 // We have been dismissed -- clean up any open requests
 - (void)dealloc {
     [[RKRequestQueue sharedQueue] cancelRequestsWithDelegate:self];
+    [_queue cancelAllRequests];
     [_queue release];
     
     [super dealloc];