ENH: Build DTI-Reg with SuperBuild ON

DTI-Reg needs BatchMake to be compiled. To avoid having to package the batchmake libraries, we compile BatchMake statically. To compile BatchMake statically, we need ITK to be build statically too (BatchMake depends on ITK). Therefore we recompile ITK, BatchMake and well as SlicerExecutionModel within DTI-Reg
Merge branch 'DTIRegStaticBatchMake'