Refactor Ipv6Service module.
+ IPv6 generic/common functionality has been moved from Ipv6Service
module to ipv6util module (Genius) in patch [1].
+ This patch handles removing of the corresponding code in Ipv6Service
module.
+ VpnManager dependency on Ipv6Service has been updated to refer to
ipv6util (Genius).
Depends-On: https://git.opendaylight.org/gerrit/#/c/72068/
JIRA: NETVIRT-1213
[1] https://git.opendaylight.org/gerrit/#/c/72794/
Change-Id: I01a90ed11ef90c2416a175e3ab92875bc76f1661
Signed-off-by: Somashekar Byrappa <somashekar.b@altencalsoftlabs.com>