ENH: Fortify baw to ensure the csv file has all valid images

If any invalid images are found in the db used to drive the processing
pipeline, then those MUST be removed before any processing is done.

This strict enforcement is to ensure that accidental path change does
not trigger massive invalidation of the entire pipeline.
COMP: only set ITK_FUTURE_LEGACY_REMOVE flag if ITK has ITK_LEGACY_REMOVE

Make sure that BRAINS build configuration matches the way ITK has
been built.

http://na-mic.org/Bug/view.php?id=3071

Note: this should really be done through a #cmakedefine in a
Configure.h.in file.
Merge pull request #26 from pieper/slicer3071-no-legacy-remove

COMP: only set ITK_FUTURE_LEGACY_REMOVE flag if ITK has ITK_LEGACY_REMOV...