created and enabled 2.0.2 branch for ns_server

Change-Id: I8a90b4f75aefbd68bb047bc186fc1010efed884e
CBD-802:  previous change re-committed to gerrit, using correct ref

A change was made to branch-2.0.2.xml using:

    git push gerrit HEAD:master            (INCORRECT)

instead of the preferred:

    git push gerrit HEAD:refs/for/master     (CORRECT)

Change-Id: I845f9790971c55f9addaf56cec94bf09682c40ca
Reviewed-on: http://review.couchbase.org/24346
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>