modifications to gollum plugin

Hi there,

I've reviewed your plugin for Gollum and made some changes. It appears that you confused the specifications for normal plugins and webapps, which use different models (according to the docs @ https://arkos.io/dev/genesis). In fact it's quite a bit simpler! :)

At any rate, I've tested this and it appears to work just fine on new installs that use standard ports (80/443). However it doesn't play nice when hosted on other ports. I think this is a function of the internal webserver not properly interpreting the full hostname as passed to it by NGINX during the proxy. If you can get me a Unicorn config or something that will make this work, I can get the rest going.

Thank you!