Add staging, production environments

[natemoo-re]

• Sets default environment to development, not hooked up to a domain
• Adds a staging environment that maps to staging.houstonbot.dev
  • Staging will have its own Discord bot for testing in other servers
• Adds a production environment that maps to houstonbot.dev
• Allows CI to deploy to different environments.
  • Only main will be allowed to deploy to production