Add !base-roles command

[mikeyaworski]

Allow users to add base roles that every member should get upon joining the discord (with optional timeout before getting it assigned).

Something like:

!base-roles <add | remove | list | clear> [role] [timeout in seconds or string form]
!base-roles add @some-role
!base-roles add @some-role "10 minutes"
!base-roles add @some-role 600

[mikeyaworski]

81d67c97d6e7ae13eab7fd79c39ea74e6f059cf9