Configure remaining options for akkounts

And refactor attributes/variables to use the various service cookbook's
own attributes.

site-cookbooks/kosmos-akkounts/attributes/default.rb

@@ -11,7 +11,7 @@ node.default['akkounts']['smtp']['domain']          = 'kosmos.org'
 node.default['akkounts']['smtp']['auth_method']     = 'plain'
 node.default['akkounts']['smtp']['enable_starttls'] = 'auto'
 
-node.default['akkounts']['discourse']['public_url'] = nil
+node.default['akkounts']['ejabberd']['admin_url'] = nil
 
 node.default['akkounts']['lndhub']['api_url'] = nil
 node.default['akkounts']['lndhub']['public_url'] = nil