Remove rulesets and port binds from logstash conf

I don't believe these are necessary. The directives that are applied within
the ruleset all relate to spooling and should be safe/sensible to apply
globally. The two port binds conflict with directives in 350-server.

This resolves two slightly separate issues:

- Ubuntu 10.04
  Ships with a version of rsyslog that doesn't support rulesets and raises
  the following warnings on startup:

        rsyslogd: the last error occured in /etc/rsyslog.d/340-logstash.conf, line 16
        rsyslogd-3003: invalid or yet-unknown config file command - have you forgotten to load a module? [try http://www.rsyslog.com/e/3003 ]
        rsyslogd: the last error occured in /etc/rsyslog.d/340-logstash.conf, line 28
        rsyslogd-3003: invalid or yet-unknown config file command - have you forgotten to load a module? [try http://www.rsyslog.com/e/3003 ]
        rsyslogd: the last error occured in /etc/rsyslog.d/340-logstash.conf, line 30
        rsyslogd-3003: invalid or yet-unknown config file command - have you forgotten to load a module? [try http://www.rsyslog.com/e/3003 ]
        rsyslogd: the last error occured in /etc/rsyslog.d/340-logstash.conf, line 33
        rsyslogd-3003: invalid or yet-unknown config file command - have you forgotten to load a module? [try http://www.rsyslog.com/e/3003 ]

- Ubuntu 12.04
  Doesn't like the duplicate port binds between 340-logstash and 350-server.
  Raises the following warning on startup and then appears not to forward
  anything to the logstash port.

        rsyslogd-2077: Could not create tcp listener, ignoring port 514. [try http://www.rsyslog.com/e/2077 ]
Clarify comment about logstash forwarding

The following line is forwarding to logstash, not syslog. We probably don't
need to know the host:port twice. But it would be useful to know the
protocol without grokking rsyslog's `@`/`@@` config syntax.
Merge pull request #1 from alphagov/logstash_remove_rulesets_binds

Remove rulesets and port binds from logstash conf