BUG: Update BRAINSTools for DWIConvert bug fixes

BRAINSTools DWIConvert module has been updated to address a problem identified the BWH team regarding images being loaded up-side-down.

In additon, some types of nifti/nrrd conversions could result in improper orientation of the images. A comprehensive bug fix was implemented to refactor the fragile old code into a consistent paradigm for managing image directions.