ENH: Creating DWI processing stream.
ENH: Changed pathing for generating python nipype wrappings.
ENH: Added features to allow for upsampling

An optional feature is adde to specifying the output image
sampling via a referenceVolume specification. Also, since
it is often needed to have reference B0 image one can also
specify extracting the first sub-volume as a separate image.
ENH: Updated SEMTools definitions with new build

Ran autopep8 to make code compliant with NIPYPE standards.
ENH: NIPYPE updated antsRegistration interface.

Units must now be specified for the shrink factors.
ENH: Added prototype for DWI processing.

This is still a work in progress, but it's a good start
towards doing DWI processing in ACPC space.