Check-in jmapel's changes to BundleTargetBody (documentation, coding...

Check-in jmapel's changes to BundleTargetBody (documentation, coding standards, unit testing) in preparation to merge this into trunk. Fixes #4079.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/branches/ipce@6924 41f8697f-d340-4b68-9986-7bafba869bb8