MB-7250:  sign "Couchbase Server" project using "Couchbase" identity

Change-Id: I6cf7aae2b85e0e94d4b152086d63c10202e05356
Reviewed-on: http://review.couchbase.org/24273
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>