Add docker support

[ogrergo]

I got fustrated having to setup a compatible node version, mongo install etc...
so I wrote this docker compose

[ogrergo]

I also changed .env.example where I left DISCORD_BOT_TOKEN= with no value instead of DISCORD_BOT_TOKEN=...
so it clearer that a first dev should leave this env var empty if not interrested by the discord bot.

At the moment, the api+job discord service try to initialize with ... as a token if I do cp .env.example .env

[SpacialCircumstances]

Thanks, looks good to me, works fine and docker support will be helpful!