cv::Mat to CDenseFeature conversion Factory and vice versa.

I have made a factory which directly converts any cvMat object into any(required) type of CDenseFeatures. 
and  CDenseFeature<float64_t> into the required type of cvMat (any)
the more I think about this the more I am convinced that this is a great idea! Also we don't have any tests for the dense features conversion right now so please add some once you move this functionality over to eh main CV2SG_Factory class