Cache resources_paths per class

Optimization for memory allocation

Author: lgebhardt

lib/jsonapi/link_builder.rb

@@ -123,7 +123,8 @@ def module_scopes_from_class(klass)
     end
 
     def resources_path(source_klass)
-      formatted_module_path_from_class(source_klass) + format_route(source_klass._type.to_s)
+      @_resources_path ||= {}
+      @_resources_path[source_klass] ||= formatted_module_path_from_class(source_klass) + format_route(source_klass._type.to_s)
     end
 
     def resource_path(source)