Add CMFreg extension

Add CMFreg extension into Slicer 4.3 branch

Documentation
https://sites.google.com/a/umich.edu/dentistry-image-computing/home-1/3d_registration_joint-_cephalometric-_experts/cmf-modules-tutorial
http://www.slicer.org/slicerWiki/index.php/Documentation/4.3/Extensions/CMFreg