Ban admin imposters

[joshfraser]

If a user signs up with the exact same name or profile picture as any of our admins, just ban them.

Possibly send them message with reason for ban.

api to ban: https://core.telegram.org/bots/api#kickchatmember

api to delete: https://core.telegram.org/bots/api#deletemessage

[wanderingstan]

Adding to this: If any user name field contains: "ICO" "Admin" "Official" "Origin" "Protocol" "Address" ... Probably more to add here.

Probably better to be overly aggressive in blocking, and let people message admins to be unblocked on false positives.

[wanderingstan]

Did some quick work on matching look-a-like letters that scammers might use: https://github.com/wanderingstan/Confusables/