ENH: Updating the source tar ball script from md5 data

This feature was just commented out, it was already there for ITK.

Change-Id: Id3bf880fb61ae88b3213dc1842d48e5aff14bee4
Merge topic 'SIMPLEITK-416_UpdateSourceTarballScript' into next

1349703 ENH: Updating the source tar ball script from md5 data