Http events v3

Convert HTTP decoder event handling to be TX-aware: https://redmine.openinfosecfoundation.org/issues/839
Fix 2 other small issues.

Changes:
- a few events were missing

Prscript:
- PR build: https://buildbot.suricata-ids.org/builders/inliniac/builds/182
- PR pcaps: https://buildbot.suricata-ids.org/builders/inliniac-pcap/builds/102