[Frontend] Hide/show Create button in mobile

open #250
open #157
Create button now hidden by default in mobile via
usage of CSS; can be re-displayed by including
'example/mobile' bundle;

platform/commonUI/general/res/sass/mobile/_mixins.scss

@@ -20,6 +20,8 @@
  * at runtime from the About dialog for additional information.
  *****************************************************************************/
 
+/* REQUIRES /platform/commonUI/general/res/sass/mobile/_constants.scss */
+
 // Phones in any orientation
 @mixin phone {
     @media #{$phonePortrait},