Error message is misleading if there are more entries in the clients group than clients

[teknofire]

In the following code, the difference of the clients in the group vs the clients themselves is using .abs.

knife-ec-backup/lib/chef/knife/ec_base.rb

Line 261 in 7dd063d

ui.warn "There are #{(existing_group_data['clients'].length - clients_in_org.length).abs} missing clients in #{org}'s client group file #{clients_group_path}. If this is not intentional do NOT proceed with a restore until corrected. `knife tidy backup clean` will auto-correct this. https://github.com/chef-customers/knife-tidy"

In the case where the clients group has 1 or more clients that no longer exist, then the message show is misleading.

There are 2 missing clients in PROD_ORG's client group file /path/organizations/PROD_ORG/groups/client.json. If this is not intentional do NOT proceed with a restore until corrected. knife tidy backup clean will auto-correct this. https://github.com/chef-customers/knife-tidy

When in fact it should say something like

There are 2 clients in clients in PROD_ORG's client group file /path/organizations/PROD_ORG/groups/client.json that no longer exist.

The way this could happen is if some clients were deleted during the knife-ec-backup, after the client group data was exported but before the client data was exported.