Exit message

Here's a PR which improve the exit message of suricata by adding the packets and drop counters. Two last commits are fixes for the live device counters which were not correctly computed.

PR builds:
- PR build: https://buildbot.suricata-ids.org/builders/regit/builds/89
- PR pcaps: https://buildbot.suricata-ids.org/builders/regit-pcap/builds/28

Ticket: https://redmine.openinfosecfoundation.org/issues/894