Add a name attribute to ManagementGroups
Change attribute name from source_reader_class to source_reader and allow it to be set via a Symbol/String that can be coerced into a class in the SourceReaders module
Change to test #respond_to? since #respond_to_missing? is a private method in Ruby 2.X
Add the class instance variable accessor management_group to ResourceSets to allow for configuration of ManagementGroups for a ResourceSet