Zoom functionality should support full width for long Designs like web pages

Summary

Trying to upload a long design fails to zoom to full width.

Steps to reproduce

See 1 minute demo video of bug: https://drive.google.com/open?id=1OqLBGrllYcROGPGhqN7E1ZlnrPAx3v7v

What is the current bug behavior?

Currently it is impossible to get to full width view. Try this design PNG from the GitLab home page:

homepage

What is the expected correct behavior?

We should pin to full width immediately with vertical scroll to match Invision and fully support website and screen design as our first MVC or at least support zooming to this state.

Possible fixes

Full_width_IF

Full_width_ELSE

cc @rkuba @jareko

Edited by Christen Dybenko