BUG: Added tests for image smart pointers pointing to Null, prior to trying to print the image info in PrintSelf
BUG: Added tests for image smart pointers pointing to Null, prior to trying to print the image info in PrintSelf

cdeepakroy/TubeTK,LucasGandel/TubeTK,matthieuheitz/TubeTK,sumedhasingla/TubeTK,KitwareMedical/TubeTK,KitwareMedical/ITKTubeTK,cdeepakroy/TubeTK,KitwareMedical/TubeTK,matthieuheitz/TubeTK,thewtex/TubeTK,KitwareMedical/ITKTubeTK,aylward/ITKTubeTK,aylward/ITKTubeTK,LucasGandel/TubeTK,aylward/ITKTubeTK,cdeepakroy/TubeTK,KitwareMedical/ITKTubeTK,thewtex/TubeTK,KitwareMedical/TubeTK,cdeepakroy/TubeTK,thewtex/TubeTK,sumedhasingla/TubeTK,sumedhasingla/TubeTK,LucasGandel/TubeTK,matthieuheitz/TubeTK,KitwareMedical/TubeTK,aylward/ITKTubeTK,KitwareMedical/ITKTubeTK,matthieuheitz/TubeTK,LucasGandel/TubeTK,thewtex/TubeTK,sumedhasingla/TubeTK