Fixed bug in Vims camera model that was causing multiple locations to be found...

Fixed bug in Vims camera model that was causing multiple locations to be found in image for single lat/lon values.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@5776 41f8697f-d340-4b68-9986-7bafba869bb8