Suricata

Will be tasked to one of the OISF devs.

In current git the first part of the solution is available: it logs the reassembled payload to alert-debuglog and unified2 if the signature matched on the reassembled stream. The app layer state, such as http, is still a todo.

App layer (such as http) state based alerts will be addressed in 1.1beta3.

Closed with the following notes:

1. prelude is still a todo (#355)
2. unified1 won't get updated as it's scheduled for removal (#353)
3. packets are logged from the stream engine segment list: this are already corrected for overlaps and retransmissions so they may not fully reflect the actual packet on the wire
4. in addition to 3, the packets in the segment list have payload only, so a fake minimal ip4/ip6 and tcp header is logged