Fix plugin filtering
Fix plugin filtering

addresses confusion between `config.optimize` and `production` env, in which `config.optimize` is true by default while ensuring plugins listed in `plugins.on` will definitely be included (unless previously filtered out by the `plugins.off` or `plugins.only` settings)
hayesgm/brunch,hellyeahllc/brunch,justinwoo/brunch,rlugojr/brunch,Flaise/brunch,PeterDaveHello/brunch,brunch/brunch,lalomartins/brunch,ondreian/brunch,kidaa/brunch