Support lazy setting of config options
Support lazy setting of config options

Similar to how the rest of Rails gained lazy config initialization
https://github.com/rails/rails/commit/39d6f9e112f2320d8c2006ee3bcc160cfa761d0a
which was later refactored to leverage framework-wide on_load hook
https://github.com/rails/rails/commit/4aded43b73ff94dbf06b4a2d2075651ce454e1d5
, ActiveResource now lazily applies configuration options from the
railtie. This allows active_resource config settings to be set within
`Rails.application.configure` block from an initializer file.

Prior to this change, ActiveResource's `set_configs` initializer ran
prior to an application's initializer file.

Shopify/activeresource,rails/activeresource