Show differences in forms and workflows between package and deploy packages.

It can be difficult to know what has changed when using the package and deploy tool to move K2 forms and workflows between environments. If previous packages are kept for archive, it would be nice to be able to do a diff comparison between the two in order to get a picture of what's changed. This is helpful when a K2 resource like a developer or admin may have left the organization and a new resource takes over.