ENH: Baseline (Phase 1) workflow complete and visually inspected
ENH: Template (Atlas) workflow complete and visually inspected
ENH: Longitudinal (Phase 2) workflow complete and visually inspected
Merge pull request #91 from dmwelch/hackmerge

ENH: Baseline (Phase 1) workflow complete and visually inspected
ENH: Remove useExplicitPDFDerivativesMode flag from BRAINSFit

This option is not used in ITKv4 optimizers. There is no need to set
that; however, this flag is not removed from the xml file to keep
backward compatibility.
WIP: make some changes
WIP: add flag to use warping
WIP: add a func to convert image to mask