org-user-remove should report back which orgs are preventing removal.
org-user-remove should report back which orgs are preventing removal.

* a new --remove-from-admin-groups flag that will
  remove the user from any org admin groups.
* If a user is in the org admin group(s) and '-R' is given, the command
  will only succeed if removing the user from the group(s) would not
  leave them empty. It will show a message listing the orgs causing
  trouble in this case.
* If a user is in the org admin group(s) and -R is not given,
  the command will refuse to continue and will list the orgs
  for which the user is still an admin.

Signed-off-by: Marc Paradise <d33c80bc45d65303e33ca83108a9952b745af9ef@chef.io>

chef/knife-opc,chef/knife-opc