It is impossible to tell whether the bridge
is being shut down intentionally or because of
an error. This is particularly important
for supervising the process, both in development
and production.
Solution: handle SIGINT and SIGTERM as a special case
and designate a separate status code (3) for intentional
shutdowns.
Also, include an example supervisor for development
mode (examples/suprevisor). Simply prepend it before
the invocation of bridge to supervise it.