Check User against Merkle Leaf every time.
Check User against Merkle Leaf every time.

Close #175; this is as close as we can get, since we have to take the server's word on what
our username is if we're loggin in via email address. We still can check that the username<->UID
mapping is correct.

keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client,keybase/client