Add post-compose rsync script
    
    - convert one-liner shell script from post compose rsync into a full
      into a full script
    - validate user input to the script
    - check for previous syncs and do not move forward if previous syncs
      were not properly completed
    - does not sync DOOMED composes but does treat them as a release
      candidate
    
    Signed-off-by: Robert Marshall <rmarshall@redhat.com>