BUG 2344 : Add the multi-node-test template for clustering integration tests

The multi-node-test template installs all the odl-clustering-test-app and ensures
that the modules.conf and module-shards.conf is generated appropriately for testing
the app in a multi-node cluster

This patch is dependent on the following controller patch,

https://git.opendaylight.org/gerrit/#/c/12705/

Change-Id: I58b2938c3125068ef895733bcec8e26050190b39
Signed-off-by: Moiz Raja <moraja@cisco.com>
(cherry picked from commit 5f1492049e63d5b0bdf0e14ea5439898c5c5d2a8)
Signed-off-by: Moiz Raja <moraja@cisco.com>