Added loading of IAK kernel specifically for Cassini support; added a Cassini...

Added loading of IAK kernel specifically for Cassini support; added a Cassini app test; removed LocalKernels class preferring system version of Kernels class; removed conditionalized obsolete code

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@2656 41f8697f-d340-4b68-9986-7bafba869bb8