fix doc link

related to issue #484
fix vim swap files ignoring
add test_atom_defaults()
improve logger overide

- add Logger.atoms() that facilitates log format override.
- add Logger.atoms_wrapper_class that permits custom wrapping.

fix #510
add jean-philippe serafin to THANKS
add fileno method to glogging.LazyWriter

fix #496
bump to 0.17.3
update travis.yml
we only care of it if gunicorn was started as a daemon

fix #466
add dd ``python -m gunicorn.app.wsgiapp``` support

fix #493
fix links in the README
Exit when the config file isn't found.

fix #469
catch ValueError when ipv6 isn't not supported on the platform

fix #479
improve STDOUT/STDERR logging redirection.

Instead of faking STDIN/STDERR to a fake object that we close on reopen,
simply redirect them to a file and reopen this one when need.

Should fix most of the issues on #309
add GUNICORN_INHERIT_FDS environment variable support

You can now pass a list of file descriptors to Gunicorn that won't be
closed when it starts. Allows someone to pass any stream to gunicorn or
set some redirection.
don't close on exec STDOUT/STDERR
systemd socket activation
add Krzysztof Urbaniak to THANKS
Close connection on error after sending started.

When the application starts yielding a body and then raises an error,
we should immediately close the connection to the client to indicate
the error.
add Alexandre Zani to THANKS