Added tolerance to match test to allow older systems to pass without requiring...

Added tolerance to match test to allow older systems to pass without requiring OS-specific truthdata.  The new tolerance may seem high at 0.8, but is accurate to 4 significant figures.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@3934 41f8697f-d340-4b68-9986-7bafba869bb8