Listviews: Deprecate ui-li-has-icon, support class ui-li-thumb

[jaspermdegroot]

Just use class ui-li-has-thumb and show people how you can override (max)height/width with custom CSS.

Change:

.ui-listview .ui-li-has-thumb > img:first-child { }

Into:

.ui-listview .ui-li-has-thumb > img:first-child,
.ui-listview .ui-li-has-thumb .ui-li-thumb { }

...so it can be used for font icons, etc.