Minor cleanup:

Minor cleanup:
 - added a modules.close()
 - print the kexec command for the bm.log to both screen and log

Added functionality:
 - Printing the set of modules that have not been unloaded yet.
 - Can list a set of modules that should be explicitly unloaded. Right
   now this has to be done by manually editing this python module.  I
   suppose in the future this should be something that can be obtained
   from a node attribute of some sort