Add symlink creation for chosen docker-compose file

[cguess]

We have three different types of docker-compose files:

1. docker-compose-with-nginx
   • The default for most people, spins everything up with an NGINX front end that also sets up SSL and is best for running on a single server
2. docker-compose-no-nginx
   • For server setups with multiple servers on the same machine and a single reverse-proxy handling the direction of traffic. This does not have NGINX included.
3. docker-compose-no-nginx-dev
   • For development of Push. This makes it easy to setup a development environment without needing NGINX or another web server to handle the traffic. Instead the plain Ruby Puma server is set up on port 3000 and the environment variables are set for hot-reloading of the code.

However, docker-compose expects the default file to be docker-compose.yml and instead now you have to use -f to point to the correct file.

Instead we should add a line to the setup scripts that asks which filed you'd like to use (with a default of docker-compose-with-nginx and the descriptions above). Then we create a symlink from docker-compose.yml to the file we'd prefer to use. Make sure to add that symlink to .gitignore as well.

Potential Issues:
Symlinks tend to point to a single file address, so if a pull is done on the repo... does this break the symlink? Test it, might even be different between mac and Linux.