def plugin_classes
       unless @plugin_classes
         load_plugins
         @plugin_classes = ObjectSpace.each_object(Class).find_all { |c| c.name =~ /Retrospec::Plugins/} - excluded_classes || []
       end
       @plugin_classes
     end
def plugin_classes
       unless @plugin_classes
         load_plugins
         @plugin_classes = ObjectSpace.each_object(Class).find_all { |c| c.name =~ /Retrospec::Plugins/} - excluded_classes || []
       end
       @plugin_classes
     end
returns an array of plugin classes by looking in the object space for all loaded classes
 that start with Retrospec::Plugins::V1