Updated documentation and testing with Ella Lee in preparation for the 3.4.0...

Updated documentation and testing with Ella Lee in preparation for the 3.4.0 release. Fixed various inconsistencies in the documentation and rewrote some parts to make it clearer. Added an example. Added two new tests to test getting the lat/lon range from the cube labels and the processing of level 1 images. Fixes #602.

git-svn-id: http://subversion.wr.usgs.gov/repos/prog/isis3/trunk@3856 41f8697f-d340-4b68-9986-7bafba869bb8