knife-ec-restore can't create backups of Servers that don't have public_key_read_access group (< 12.5.0)

[glasschef]

Specific Issue

We now expect the Chef Server to contain the public_key_read_access group for an organization. If it doesn't we can't back it up.

General Issue

Over the last few Chef Server releases a number of changes have been made to the default layout of an organization and default ACLs. If we don't account for all of the possible past structures of the Chef Server groups, then knife-ec-backup can not be used reliably facilitate migrations from old servers to new.

Similar in nature to #79

[glasschef]

Attempting to back up Chef Server 12.1.2:

root@chef-e:~# /opt/chefdk/embedded/bin/knife ec backup backy -c /etc/opscode/pivotal.rb 
Downloading Users
Downloading organization object for demo from https://127.0.0.1/organizations/demo
Copying /acls/groups/billing-admins.json
Copying /groups/billing-admins.json
Copying /acls/groups/public_key_read_access.json
ERROR: Server returned error 500 for https://127.0.0.1/organizations/demo/groups/public_key_read_access/_acl, retrying 1/5 in 3s
ERROR: Server returned error 500 for https://127.0.0.1/organizations/demo/groups/public_key_read_access/_acl, retrying 2/5 in 6s
ERROR: Server returned error 500 for https://127.0.0.1/organizations/demo/groups/public_key_read_access/_acl, retrying 3/5 in 12s
ERROR: Server returned error 500 for https://127.0.0.1/organizations/demo/groups/public_key_read_access/_acl, retrying 4/5 in 23s
ERROR: Server returned error 500 for https://127.0.0.1/organizations/demo/groups/public_key_read_access/_acl, retrying 5/5 in 47s

erchef logs from Chef Server :

==> /var/log/opscode/opscode-erchef/crash.log <==
2017-07-05 20:56:49 =ERROR REPORT====
{<<"method=GET; path=/organizations/demo/groups/public_key_read_access/_acl; status=500; ">>,{error,function_clause,[{chef_wm_util,not_found_message,[group,<<"public_key_read_access">>],[{file,"src/chef_wm_util.erl"},{line,119}]},{oc_chef_wm_acl,check_acl_auth,2,[{file,"src/oc_chef_wm_acl.erl"},{line,117}]},{oc_chef_wm_base,forbidden,2,[{file,"src/oc_chef_wm_base.erl"},{line,142}]},{webmachine_resource,resource_call,3,[{file,"src/webmachine_resource.erl"},{line,186}]},{webmachine_resource,do,3,[{file,"src/webmachine_resource.erl"},{line,142}]},{webmachine_decision_core,resource_call,1,[{file,"src/webmachine_decision_core.erl"},{line,48}]},{webmachine_decision_core,decision,1,[{file,"src/webmachine_decision_core.erl"},{line,225}]},{webmachine_decision_core,handle_request,2,[{file,"src/webmachine_decision_core.erl"},{line,33}]}]}}