This commit removes the `peerport` and `rpcport` config options and
adds `listen`, `rpclisten`, and `restlisten` options to allow setting
one or multiple interfaces to listen on for incoming connections.
It also adds a `nolisten` option to allow disabling the listener for
incoming peer connections.
This commit adds additional documentation to the sample-lnd.conf, and
also ensures that users are able to drop it in without any issues. The
prior version left the namespace off several of the arguments, rendering
it unusable.
Fixes#462.
