Proper fix T40156 Cycles Baking and applyRotation issues

This should be the final fix for the applyrotation issue. It baffles me
that the fix involves discarding the scale transformations for the
normals but it works so I'm happy with it.

Reviewers: campbellbarton

Differential Revision: https://developer.blender.org/D554
Fix T40422: EdgeSlide works incorrectly with boundry edges