beakerrepos.py: pass --name explicitly
    
    The current nightly composes identify themselves as just
    "Fedora Rawhide" in the .treeinfo file, rather than distinguished by
    date as in "Fedora-Rawhide-20170829.n.0". This means when they are
    imported into Beaker they will all be considered as the same tree, even
    though they are different snapshots.
    
    As a workaround, pass --name when invoking beaker-import to make the
    trees show up with their proper name.
    
    This means we can't use 'location' as a fallback for 'compose_id'
    anymore because the 'location' URL isn't usable as a distro tree name in
    Beaker. But that should be okay since all recent compose messages have
    a proper value for the 'compose_id' key.