Merge pull request #174 from adrienkaiser/update-DTIAtlasBuilder

BUG: Fix compilation errors on mac and give DTIReg the path to ANTS if Slicer Extension
Added SlicerIGT extension definition.
Merge pull request #175 from ungi/update-SlicerIGT

Add SlicerIGT extension
BUG: fix given paths for DTIReg in Testing