Deduplication Functionality

This branch introduces some basic deduplication functionality into OpenBR.  The idea is you can specify an algorithm and use its resulting match scores when comparing a gallery to itself, along with a threshold, to remove duplicates.  For my purposes, I have been using only Identical distance as I am only concerned about identical images, but it works well for duplicate subjects assuming you know the match score threshold that indicates a duplicate subject.  It is a bit clunky as it reads an entire gallery into memory as opposed to doing it block by block, but I think it's still useful in this state.

In an unrelated note, I'm just learning about git's rebase functionality and fudged some of the commit history - sorry about that.