You can clone with
HTTPS or Subversion.
since plone.app.imaging is not part of Plone 5 the property-sheet 'imaging_properties' is missing.
The problem with plone.app.imaging is that is pulls in Archetypes. We need to either make it not do that so we can include it in Plone 5, or move the property sheet to another package. Actually maybe it should be part of the control panel plip and moving settings to the registry.
Ah, I see you are one step ahead of me and moved it already. Cool. :)
Fixed in plone/Products.CMFPlone@f97e49f, plone/plone.app.imaging@eefd46a and plone/plone.app.upgrade@c8d4270
Move imaging_properties and utilities to CMFPlone