Allow K1,K2 refirement combination
Allow K1,K2 refirement combination

It is now possible to refine only radial distortion
with new Ceres based bundler and this new combination
is already used in Blender.

Nazg-Gul/libmv,Nazg-Gul/libmv,Nazg-Gul/libmv,Nazg-Gul/libmv,Nazg-Gul/libmv