Cluster 1 requirement is a nuisance

[ronkorving]

We all want installation and usage to be as easy as possible, and I think it would be great if people didn't have to configure their MAGE application specifically for "npm run develop" to function.

• It's possible that sometimes they'll boot up the app with, and sometimes without the console, and that should not require two separate config files.
• What happens when I forget to configure my app appropriately, or I'm on the wrong NODE_ENV? How scared should I be for things to go wrong? Not having to worry is a good thing.

Hypothetical solutions:

• Allow mage-console to work with >1 worker, and have it gracefully shutdown if cluster is false (something we may want to remove support for in a future MAGE version anyway).
• Let mage-console override application config to set cluster to 1. It's quite possible there's no reliable way to do this today, but maybe we need to work on a way to make this possible.

[stelcheck]

The proper solution would be to have mage-console auto-configure MAGE, but that's just not possible from what I can tell: mage/mage#67

For now, the way things works is the safest way I can think of; besides, you could always create an environments.yml config and use an environment variable in-project to get the job done (I do this on some of my projects to force-disable certain things during unit tests). However, this just cannot be done from a module.