Use file cache when accessing remote files during testing

hist/histpainter/src/THistPainter.cxx

test/stressGraphics.cxx

test/stressHistogram.cxx

test/stressRooFit.cxx

test/stressTMVA.cxx

tmva/pymva/test/Classification.C

tmva/rmva/test/Classification.C

tutorials/hist/th2polyUSA.C

tutorials/tmva/TMVAClassification.C

tutorials/tmva/TMVAClassificationApplication.C

tutorials/tmva/TMVACrossValidation.C

tutorials/tmva/TMVARegression.C

tutorials/tmva/TMVARegressionApplication.C