enable translation for strings in customlayout.js

Bug 1371460: Some strings still where hard coded in English in htdocs/js/customlayout.js. This patch puts them into lang/en.utf8/view.php for translation and adds them to the smarty-template in layout.php

Change-Id: I182673f18de2ca5d50d4cfa0f4461a4699695bd5
Signed-off-by: Tobias Zeuch <tobias.zeuch@kit.edu>