Title page update.
Update SoftwarePreparation1 and comment out Overview, OpenCV Bridge.
Updates to SoftwarePreparation2
Updates to SoftwareEnvironment.tex
Updates to the SimpleITK section.
Update to the LevelSets.
Fix RegistrationExercises argument parsing.
Updates to Registration.
Add Registration diagrams.

Luis' Kitware tutorial material.
Add documentation on how to contribute.
Merge branch 'MadisonJanuary2013'