Changed use of ternary operator to standard if-else for compatability with...

Changed use of ternary operator to standard if-else for compatability with older versions of Python on CentOS systems

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@2899 41f8697f-d340-4b68-9986-7bafba869bb8