Signal based file rotation - v3.

Changes from previous PRs:
- Moved rotation notification to the main loop.  The handle now just sets a flag.
- Notification done by registering a flag, not a call back function as all
  the callbacks were simply setting a flag.
- Add support for all loggers that don't log to a timestamped file.

Previous PRs:
https://github.com/inliniac/suricata/pull/856
https://github.com/inliniac/suricata/pull/829

Buildbot output:
- PR build: https://buildbot.suricata-ids.org/builders/jasonish/builds/59
- PR pcaps: https://buildbot.suricata-ids.org/builders/jasonish-pcap/builds/13

Sample logrotate configuration:

    /var/log/suricata/*.log /var/log/suricata/*.json
    {
        rotate 3
        missingok
        nocompress
        create
        sharedscripts
        postrotate
                /bin/kill -HUP $(cat /var/run/suricata.pid)
        endscript
    }