Update with lifeSpan of objects

Objects must have lived atleast a specific amount of time before they
may be kept if considered last.
Development of additional, better management has begun and some
aditional class methods have been added.
Tracking upgrade

* Objects must have lived a minimum number of frames before considered
as REAL objects.
* Lost objects are removed if they have been lost for a specified number
of frames.
* The algorithm is well commented and clearly structured.
Merge remote-tracking branch 'origin/master' into Tracking

Conflicts:
	src/ImageProcessing/BackgroundModelMoG.cpp
	src/ImageProcessing/ForegroundRegionExtractorDefault.cpp
Merged with master
Merge remote-tracking branch 'origin/master' into Tracking

Conflicts:
	conf/dense_conf.yml
Added interface and comments

Left Object as is (made it into a struct though, making it a little more
acceptable that the variables are public, since it is a kind of
container...).
Merge pull request #39 from GroupDenseKitchen/Tracking

Tracking. Left Object as is since a dedicated issue about it has been created.