logging: haproxy to /var/log/haproxy.log

This fixes the HAProxy logging issue we were running into. I previously changed `haproxy.cfg` to log over `udp/localhost:514` but that loses the ability for rsyslog to test based on the `$programname` field. We also now explicitly lay down and override the `49-haproxy.conf` that comes from the PPA.

@dlundquist @paulczar @craigtracey