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/Add.hs

@@ -146,7 +146,7 @@ perform file = do
 
 cleanup :: Key -> Bool -> CommandCleanup
 cleanup key hascontent = do
-	maybeShowJSON $ JSONObject [("key", key2file key)]
+	maybeShowJSON $ JSONChunk [("key", key2file key)]
 	when hascontent $
 		logStatus key InfoPresent
 	return True