Modernize slider snippet
Modernize slider snippet

Don't use practices, which are not encouraged in Tabris 2.x anymore,
e.g. using property setters/getters instead of fields and utilizing the
layoutData property.

Change-Id: I1108fe7edc17c167a639c5bdc5f6b0a660c379bc

eclipsesource/tabris-js,eclipsesource/tabris-js,eclipsesource/tabris-js