Add docker-compose to launch domain server, ice server, and metaverse server.

[hasbegun]

Summary: Add docker-compose.yml file to start and stop the services.
         1. Add 'vircadia-mongo' to split the DB from metaverser server.
         2. Start and stop domain-server, ice-server, metaverse server, and mongo db.
         TODO: There is still an error from metaverse server that needs
         to be fixed. However, this commit resolves most common mongodb
         related errors.

[Misterblue]

I haven't tried running this yet, but one comment: I notice in docker-compose.yml that the domain-server depends on the ice-server image. There are two running configurations:

1. running a metaverse: where you need the metaverse-server, ice-server, and mongo-db;
2. running a domain-server: just hosting a space and relying on a metaverse already running.

Thus, I think the domain-server configuration should just be running a domain-server with the parameters to connect to an existing meteverse-server and an ice-server.

I'll have more comments after I've run this.