Allow starting a subset of integrations

[raing3]

Ideas:

• "Might be an idea to add a gitignored config file or something. So you can turn containers on/off if you want and only have a subset running easily. Instead of needing to edit the yml file."
• Potentially have dependency tree defined in config.
• Potentially CLI argument for "up" (and similar commands?) using similar syntax to Docker CLI: https://docs.docker.com/engine/reference/commandline/ps/#filtering

[raing3]

Probably would be better to implement something like this: https://github.com/vmorganp/Lazytainer

Allow containers to (optionally?) be set to lazy and then only load them when we receive traffic through the gateway on one of the routes they handle.