The error message at startup when the address/port could not be bound
was confusing:
hg serve
abort: cannot start server: Address already in use
Be more explicit:
$ hg serve -a localhost
abort: cannot start server at 'localhost:8000': Address already in use
Also be more explicit on success, showing hostname and ip address/port:
$ hg -v serve -a localhost -p 80
listening at http://localhost/ (127.0.0.1:80)
We are careful to handle a missconfigured machine whose hostname does not
resolve, falling back to the address given at the command line.
Remove a dead-code error message.
create_server was looking only at the root ui object, ignoring any
settings from .hg/hgrc. To keep respecting command-line arguments,
commands.serve must also call repo.ui.setconfig.
