Allow other DCS servers with server= param

[richmahn]

Suggest that when.you want to change the DCS server that Gateway Admin uses, to be able to give any DCS URL, not just "qa". DCS can even be ran local and is self contained (including the catalog API), meaning it can even be ran as a Docker container. I suggest that the param to use something other than git.door43.org be:

server=[:]

For example:

server=qa.door43.org
server=https://develop.door43.org
server=localhost:3000
server=127.0.0.1
server=http://dcs

If no port, assumes port 80. If domain is localhost or 127.0.0.1 assume protocol to be http, unless one is given like in the 2nd and last example. You could still keep "server=qa" to then resolve to https://qa.door43.org, but allow custom domain/port as well.