[surrogate_model] added exploration scores for candidates for MC+BayesOptDesign.

BayesValidRox/PostProcessing/PostProcessing.py

BayesValidRox/PyLink/FuncForwardModel.py

BayesValidRox/surrogate_models/surrogate_models.py

BayesValidRox/tests/AnalyticalFunction/AnalyticalFunction.py

...idRox/tests/AnalyticalFunction/AnalyticalFunction_Test.py

...ValidRox/tests/BeamTest/PosteriorGeneration/Posterior.csv

BayesValidRox/tests/BraninTest/Branin_Test.py

BayesValidRox/tests/IshigamiTest/Test_Ishigami.py