Refactor Scalable functionality

This commit transforms Scalable into a calculation engine that is
delivered by objects with dimensions. The Scalable object is responsible
for all calculations and adjustments that relate to the dimensions
of a given object.

As a result, everything that relates to size calculation has been
touched.

On top of that, MediaSizeWidget has been adjusted to work with
Scalable objects and also display the dimensions through the
dimensions widget.

This is a breaking change, fixed in MW by change
I017a017924f544cc8bc9b7d8245335759ae0e890

Change-Id: Ie7ca3bbbe5d0287c7ce17d296c1827b8213ea950
Merge "Refactor Scalable functionality"