move away from apache in favor of nginx

[dano-reisys]

@FuhuXia is there a particular reason we went with apache?
Me and @JJediny had a conversation about this and we thought that it makes sense to switch to nginx.

[FuhuXia]

No particular reason. I guess that is the most popular way to install ckan, which make it easy to find answer for any problems.

[dano-reisys]

https://gist.github.com/nigelbabu/076ad12c13b2071de8e1

[dano-reisys]

@JJediny Do we still want to use nginx as a webserver for ckan? We are already using nginx as a proxy https://github.com/GSA/catalog-nginx