fix model, add calibrated scaling
fix model, add calibrated scaling

Updates camera model to correct a “cross-spin flip”.  This means tuning
the rotation and tilt parameters is no longer needed (as long as Juno
spin axis maintains its non-torquing orientation).

Produces outputs with a 30 pixels per degree spacing calibrated in the
along-spin direction. Cross spin spacing has not been calibrated, but
is probably close to 30 pixels per degree.

Supports scaling to 15, 60, and 90 pixels per degree.  (Though excess
memory use may lead to a crash if scaling up large (full-spin) data
takes.)

BrianSwift/JunoCam,BrianSwift/JunoCam