record user key is broken

[okwme]

as part of createNewUserKey we attempt to save the mnemonic phrase of the user in a directory called keys. First off the cwd is relevant to the running of the slackbot binary, and not the user's home directory (for instance). secondly the command fails silently.

We should first off confirm whether it's possible to save the user's keys this way (i think the mnemonic phrase might not actually be part of the stdout). If so, we should fix the command so that keys are saved (maybe even throw an error that prevents the creation of a user where this step fails). Finally we should re-migrate all the users keys so that we have a written backup of all of them. All of this would be in service of the functionality to allow users to receive a copy of their mnemonic phrase in order to use their keys outside of slack.

[okwme]

i think out of those steps (1-4), 1 and 2 are the most valuable but 3 and 4 should be saved for another issue.