Add user creation date to API data

Fixes #1390

Author: JasonBarnabe

app/models/user.rb

@@ -205,9 +205,9 @@ def favorite_script_set
 
   def serializable_hash(options = nil)
     sleazy = options&.[](:sleazy)
-    h = super({ only: [:id, :name] }.merge(options || {})).merge({
-                                                                   url: Rails.application.routes.url_helpers.user_url(nil, self, **(sleazy ? { host: 'sleazyfork.org' } : {})),
-                                                                 })
+    h = super({ only: [:id, :name, :created_at] }.merge(options || {})).merge({
+                                                                                url: Rails.application.routes.url_helpers.user_url(nil, self, **(sleazy ? { host: 'sleazyfork.org' } : {})),
+                                                                              })
     # rename listable_scripts to scripts
     unless h['listable_scripts'].nil?
       h['scripts'] = h['listable_scripts']