Bug 6589 adding support for hwvtep devices ha

Bug 6589 adding support for hwvtep devices ha

Added template code to copy the data between ha and child nodes.
When a child node connects copy its operational data to its ha operational
node.
When operational update is received on child node , copy that operational
update to its ha operational node.
When some config update happens on ha node, copy that config update to
child node.

An add/delete Macs.PhysicalLocator,TerminationPoint,Switch update from
child is immediately pushed to parent ha node.
Duplicate updates from childs is properly filtered out while copying to
the parent ha node.

Depends-On: I7ad598fe9604aae9ad1df71270f1cba5b212a634
https://git.opendaylight.org/gerrit/#/c/44670/
Patch was reverted until netvirt catches up.

Change-Id: I091ab1f1fa8b82445918e1030f20136421286299
Signed-off-by: Akash <a.k.sahu@ericsson.com>