Initialize the banding mode. Others really shouldn't be asking for it when the...

Initialize the banding mode. Others really shouldn't be asking for it when the tool isn't active... but it causes no harm in this case. Fixed usage of uninitialized variable.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@2583 41f8697f-d340-4b68-9986-7bafba869bb8