Stix ipwatch v1.11

Adds support for STIX-based indicators for feature #1095.

From previous PR: #1096:
Ensured each commit compiles.
Modified WatchListData data structure in util-ipwatchlist.h to use a char* instead of a Signature.
Resolved comments from #1096 

From previous PR: #1060:
Organized and updated unit test function names to start with upper case letter in detect-watchlist.c and detect-smtp-indicators.c.
Modified InitWatchDataFully to properly invoke free.
Updated to meet QA standards.

This is a match function that is called per packet, which makes it rather inefficient.

I would prefer an approach similar to HTTP, where we have a so called 'inspection engine'. See https://github.com/inliniac/suricata/blob/master/src/detect-engine.c#L136