Pair requests are sent on all network interfaces, and contain the best
available hostname to use to contact the host on that interface.
Added a pairing in progress page.
Revert "reduce some boilerplate using ghc extensions", because it caused
overlapping instances for Text.
Actually 3 forms in one, this handles the initial passphrase entry, and the
confirmation, and also varys wording if the same user or a different user
is confirming.
