Add moderation tools

[ShadyMedic]

It seems that some kind of functionality, that would allow the mods to temporary ban some users or at least let them see their reasoning for the punishment would be useful. Apparently, we want to have only one bot on the Discord server, so it would go to this repository.

What the bot should be able to do:

1. Display reasoning - RedMinima will send DM to the punished player with a message specified by the mod
2. Temporary bans - The punished player will be unbanned after a specified time and Red Minima will send them DM to remind them of the fact that they can rejoin if they still want to be part of the project.
3. Official warning system - RedMinima should be able to send the punished player a nicely formated DM with a warning. The player should see that it's a serious deal
4. Auditioning - a mod should be able to easily see a log of user's punishments, so they can decide the type of punishment. Date when the punishments were issued need to be displayed too.

Suggested syntax of commands:
!ban <user> <reason>
!tempban <user> <x> <minutes/hours/days/months> <reason>
!kick <user> <reason>
!warn <user> <reason>
!log <user> <max-records>

Original message on Discord