add success message to watch / ignore category methods

public/language/en_GB/category.json

@@ -7,5 +7,9 @@
 	"no_replies": "No one has replied",
 
 	"share_this_category": "Share this category",
-	"ignore": "Ignore"
+	"watch": "Watch",
+	"ignore": "Ignore",
+
+	"watch.message": "You are now watching updates from this category",
+	"ignore.message": "You are now ignoring updates from this category"
 }

public/src/client/category.js

@@ -73,6 +73,8 @@ define('forum/category', [
 
 				$('.watch').toggleClass('hidden', command === 'watch');
 				$('.ignore').toggleClass('hidden', command === 'ignore');
+
+				app.alertSuccess('[[category:' + command + '.message]]')
 			});
 		});
 	}