Refs #969 - Proxy-side changes for serving templates from the proxy

An update to @GregSutcliffe's original PR (https://github.com/theforeman/smart-proxy/pull/100/files). Ports his original feature to the new plugin api.
if the uri is 'https://google.com/'
the request it would make to the server would be
GET https://google.com/ 
instead of 
GET /

i saw that it was present in settings.yml in develop branch...so thought it would be  to use it.
going to use a fail fast( couldn't find an existing example yet).