Adding possibility to use a different cache-backend for locking and caching

- Renaming *LockDriver to *Lock since it isn't a "driver" anymore

src/Core/Cache/APCuCache.php

@@ -153,4 +153,9 @@ class APCuCache extends AbstractCache implements IMemoryCache
 
 		return true;
 	}
+
+	public function __toString()
+	{
+		return self::TYPE_APCU;
+	}
 }