Temporary fix for restoring HTTP events

Since the libhtp 0.5.x integration most HTTP events were not longer working. We're working with libhtp upstream to create a permanent solution for event handling, but meanwhile this PR restores most of the events, and adds 2 new.

https://buildbot.suricata-ids.org/builders/inliniac/builds/14
https://redmine.openinfosecfoundation.org/issues/982

Changes since https://github.com/inliniac/suricata/pull/570:
- minor comment fix