Add rebuildlist to fedcontainer_rc
    
    At the moment, the Factory 2.0 and OSBS work for layered image
    rebuilds is not ready to production use so we're going to have to
    identify what images to rebuild (right now, all of them) and then
    actually rebuild them. This patch introduces that data collection so
    we can perform builds.
    
    Also, a previously known bug was found and resolved in this patch.
    There was a requests call in the list comprehension which did not
    allow for any amount of error checking.
    
    Signed-off-by: Adam Miller <maxamillion@fedoraproject.org>