Bug 6278: Move opendaylight-karaf-empty to odlparent

Bug 6278: Move opendaylight-karaf-empty to odlparent

Move opendaylight-karaf-empty from controller to odlparent. As with
moves of other artifacts, the following process will happen:

1) Copy opendaylight-karaf-empty into odlparent and adjust the groupId.
   The patch that handled the copy work is:

   https://git.opendaylight.org/gerrit/#/c/43988/

2) Change opendaylight-karaf-empty in controller to derive from odlparent's
   opendaylight-karaf-empty.  This is handled in this patch.

3) Change references to use the artifact added in #1.

4) Deprecate and remove controller's opendaylight-karaf-empty.

This patch just handles #2, re-parenting the existing controller
opendaylight-karaf-empty such that it derives from odlparent's
opendaylight-karaf-empty (added in #1).

Change-Id: Ifbfedd8a06f5f03900277d005906af83220707cc
Signed-off-by: Ryan Goulding <ryandgoulding@gmail.com>