Fix hook registration and smarty modulecode argument

Module code argument was parsed as int, but this is generaly a string
        modifié:         core/lib/Thelia/Core/Template/Smarty/Plugins/Hook.php

Hook activate column was set as null on update ( 2nd, 3rd, ... activation of a module )
	modifié:         core/lib/Thelia/Module/BaseModule.php