Migrate to karaf4 for the local karaf distribution

Migrate to karaf4 for the local karaf distribution

Several folks have put in incredible effort to make karaf4 a reality in ODL.
Kudos to those folks for this great effort.  This patch officially converts
netconf's local karaf distribution to use odlparent's karaf4-parent artifact.

The karaf4 implementation will still be accessible at the following well-known
path:

> karaf/target/assembly

Change-Id: I00a1e5b93f5c57447e95a714d40e0635b5747393
Signed-off-by: Ryan Goulding <ryandgoulding@gmail.com>
(cherry picked from commit cb106fb29817db6c9e39ae6f47a3c3276d8e5e92)