Rename artifacts

Rename artifacts

Original contribution used org.opendaylight.protocol as the artifact
group ID. The repository name implies this needs to change to
org.opendaylight.bgpcep to keep consistency between repository name and
artifacts it creates. This patch renames the artifacts without touching
the packages contained in them.

Change-Id: Ic26d5fe7a21a65521ab6d5aa56dc6172719202c5
Signed-off-by: Robert Varga <rovarga@cisco.com>