Add language strings

lang/en_us.php

@@ -29,4 +29,6 @@ define("STRINGS", [
     "login server user data error" => "The login server refused to provide account information.  Try again or contact technical support.",
     "captcha error" => "There was a problem with the CAPTCHA (robot test).  Try again.",
     "home" => "Home",
+    "point of sale" => "Point of Sale",
+    "barcode" => "Barcode"
 ]);