Removed dependency on json library; all JSON is now handled by aeson.

I've eyeballed all --json commands, and the only difference should be
that some fields are re-ordered.

Command/AddUrl.hs

@@ -356,7 +356,7 @@ cleanup u url file key mtmp = case mtmp of
 			)
   where
 	go = do
-		maybeShowJSON $ JSONObject [("key", key2file key)]
+		maybeShowJSON $ JSONChunk [("key", key2file key)]
 		when (isJust mtmp) $
 			logStatus key InfoPresent
 		setUrlPresent u key url