ENH: Update the constructors of all the available classifiers with the OpenCV default parameters in TrainImagesClassifier

DOC: Improvement of the documentation of the OpenCV SVM classifier in the TrainImagesClassifier application

ENH: disparity metric thresholding is now defined as optional parameter in StereoFramework application JIRA #OTB-375.

ENH: add log for memory usage and inverse subsampling factor optionnal parameter to avoid memory consumption in StereoFramework JIRA #OTB-375.

ENH: inverse/direct blockmatching strategy to check bijection consistency is available in StereoFramework application using bij option JIRA #OTB-375

BUG: Inversion of parameters in the constructor of the GBT classifier in the TrainImagesClassifier application

TEST: Add tests of several classifiers for the OpenCV framework in the TrainImagesClassifier application

ENH: Revert: handling ParameterType_Float SVM parameters for the OpenCV framework in the TrainImagesClassifier application