ENH: Update ITK to 4.12.2; BUG: Clone ITK from Github instead of itk.org
ENH: Update ITK to 4.12.2; BUG: Clone ITK from Github instead of itk.org

Fixes clone failure due to Kitware’s SSL certificate

kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix,kaspermarstal/SimpleElastix