set omnios publisher first

When using profiles with build_zfs_send -p, the omnios publisher is set as the last in the publisher order. This breaks zone creation:

    # zoneadm -z foo install
    A ZFS file system has been created for this zone.
       Publisher: Using niksula.hut.fi (http://pkg.niksula.hut.fi/ ).
       Publisher: Using omnios (http://pkg.omniti.com/omnios/release/).
           Image: Preparing at /zones/foo/root.
           Cache: Using /var/pkg/publisher.
    Sanity Check: Looking for 'entire' incorporation.
    ERROR: Unable to locate the incorporation 'entire@11,5.11-0.151006:20131210T224515Z' in the preferred publisher 'niksula.hut.fi'.
    Use -P to supply a publisher which contains this package.

The fix is trivial, just set the omnios publisher as first in order.