Feature/environment configuration

[thmsndk]

The following PR aims to move more configurations out into configuration files that are not comitted to git, this way you have more control on the specific server installation.

• Fixes an issue where api/characters_and_servers would return a hardcoded 192.168.1.125 ip when running in SDK mode
  • This allows headless (caracAL, ALClient) / custom clients that rely on that api response to connect to the websocket to connect properly
• Added new environment.py
  • you can configure game_name, appengine_id, live_domain, sdk_domain
  • The hardcoded IP_TO_SUBDOMAIN has also been moved here.
• DISCORD
  • Moved some hardcoded links to #welcome into environment.py
  • You can now customize your discord bot token and channels in variables.js
  • You can now enable discord in sdk mode
  • discord integration is disabled by default in template.variables.js
• You can now override values in server.js mode
  • this allows you to disable the drm_check that causes the authfail debuff
  • you can also disable / enable the notverified_debuff
  • any property inside mode can be changed / adjusted

closes #94

-WARNING: This PR will require the live servers to update their config file(s)

• secrets.py the discord url for the welcome invite needs to be supplied
• variables.js make sure to configure the discord section to be ENABLED, the bot TOKEN and the EVENT_CHANNELS
  • discord_url has been replaced in the config with a discord section
• add the new environment.py the IP_TO_SUBDOMAIN should be untouched, if running in SDK mode, make sure to map REQUEST_IP_TO_HOSTNAME properly

[thmsndk]

I currently can't think of other things I want to add to this PR, reviews will be much appreciated. I have tested it on my local dev server, and everything works as expected as far as I can tell.

[Telokis]

@thmsndk Since this PR is big and I've left several comments, I'll let you tell me when you consider it ready for me to take another look at it.
Please write a small word after each of my open conversations to let me know how you've addressed it so I can better keep track.

[thmsndk]

I'm unsure if my latest commit will break the live production servers as I've been messing around with how "https_mode" is utilized https://github.com/kaansoral/adventureland/pull/116/commits/8c20b823f373de25948b7c0ccc611ac95d90cafd

More research and testing is needed, but server_eval is now fixed on my local docker environment.