add nworkers_changed hook

This hook will be called whenever the number of workers is set.
handle size 0 read by returning empty buffer

It appears the original author meant to return b"" when size == 0 instead of raise ValueError("Size must be positive.")
add David Vincelli to THANKS.
make sure we don't prematuraly close the fd of the worker tmp file.

fix #407
Append acceptors in EventletWorker
add Adnane Belmadiaf to THANKS.
s/create_sockeSt/create_sockets
PEP8 fixes
s/optparse/argparse
add syslog support.

Add options to setup logging to syslog:

- `--log-syslog`: enable syslog. It default to `/var/run/syslog` on darwin,
  `/var/run/log` on freebsd, `/dev/log` on openbsd and udp://localhost:514 for
  other platforms.
- `--log-syslog-prefix: Pass the parameter to use as the program name
- `--log-syslog-to`: Setup the syslog address to send message. Address startinf
  by udp:// will send to udp, unix:// to a unix socket and tcp:// to tcp (useful
  for rsyslog)

fix #452 .
add line
fix syslog prefix
say hello to 0.17.0
document syslog handler code
document a little more --log-syslog-prefix option
fix help formatting
archive 2012 news
display latest version on the website
add syslog facility name setting
ArgumentParser no longer accepts version in Python 3.3