Change the parameter FLUXUNITS to UNITS. Changed the default value of the...

Change the parameter FLUXUNITS to UNITS. Changed the default value of the UNITS parameter to I/F (instead of INTENSITY). Fixes #219.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@4634 41f8697f-d340-4b68-9986-7bafba869bb8