fix(list): use hex for unicode character to avoid encoding errors

List component bullets appear as • instead of bullets utf-8 \2022.
Problem was showing up in Android and iOS after using Cordova to create the app.
Traced the issue and not a Cordova problem but a CSS issue.

In usual browsers there is no visual difference, but using hex notation is a more clean implementation anyway

src/themes/default/elements/list.variables

@@ -162,7 +162,7 @@
 @bulletOffset: -@bulletDistance;
 
 @bulletOpacity: 1;
-@bulletCharacter: '•';
+@bulletCharacter: '\2022';
 @bulletColor: inherit;
 @bulletLinkColor: @textColor;
 @bulletVerticalAlign: top;