In this commit, we move to start requiring the payment addr feature bit
in the invoices we produce. With this change, if a user attempts to pay
one of our invoices (assuming they're also an lnd node), then they'll
receive an error when they attempt to pay. At this point, *most* lnd
nodes should be on v0.11 at this point, and this change will notify any
lagging wallet authors to update, as these payments are generally more
secure.