Update buildout.cfg

Correct source for plone.scale
Replace deprecated test assert statements.
Move imaging_properties and utilities to Products.CMFPlone
Update icon_expr Value in controlpanel.xml

This tries to make control panel icon not broken in Plone 5.
Add missing dependency
Merge pull request #5 from l34marr/patch-1

Update icon_expr Value in controlpanel.xml
fix other references to icon