[IMP] pos_restaurant: Order printers with HTTPS

To use a kitchen printer, the user can only enter the IP of the Box and
it would be transformed into an URL with the protocol and port number.
This only supported HTTP so people that used HTTPS needed to enter the
full url to their Box.

addons/pos_restaurant/static/src/js/multiprint.js

@@ -12,9 +12,9 @@ models.PosModel = models.PosModel.extend({
     create_printer: function (config) {
         var url = config.proxy_ip || '';
         if(url.indexOf('//') < 0) {
-            url = 'http://' + url;
+            url = window.location.protocol + '//' + url;
         }
-        if(url.indexOf(':', url.indexOf('//') + 2) < 0) {
+        if(url.indexOf(':', url.indexOf('//') + 2) < 0 && window.location.protocol !== 'https:') {
             url = url + ':8069';
         }
         return new Printer(url, this);