Added default language pack (en-gb)

catalog/api/cart.php

@@ -0,0 +1,10 @@
+<?php
+// Text
+$_['text_success']     = 'Success: You have modified your shopping cart!';
+
+// Error
+$_['error_permission'] = 'Warning: You do not have permission to access the API!';
+$_['error_stock']      = 'Products marked with *** are not available in the desired quantity or not in stock!';
+$_['error_minimum']    = 'Minimum order amount for %s is %s!';
+$_['error_store']      = 'Product can not be bought from the store you have choosen!';
+$_['error_required']   = '%s required!';