ENH: Move clone URL from gitub.com to itk.org

The clone URL at http://itk.org/ITKExamples.git removes the dependency on
Github, and is in sync with itk.org/ITK.git.

Change-Id: I2a3cb63fb0c22d638f23168f5d2c84f7f345113a
Merge "ENH: Move clone URL from gitub.com to itk.org"