Password key file

[orthecreedence]

This would use the user:get-login-token / user:login-from-token feature. Just need an interface in the UI for this. Note that we should also add a new core endpoint for changing the password with a key file instead of a username/password.

• Login via key file
• Change password via key file

We should let people know they need to re-generate this file when they change their password.

NOTE: People need to know how dangerous it is to leave this token laying around! Add some messaging.