consider adding a deployment option to automatically shut down all servers

[blake-mealey]

Potential config API:

environments:
  - name: production
    restartServers: true

[blake-mealey]

Would this be a useful feature for developers? I feel like this could be a bit heavy-handed, especially for patch releases. Perhaps it should be a command-line flag (e.g. --restart-servers-post-deploy) instead so that it is more of a one-time thing?