MB-7250:  sign the app at the project level, using a com.couchbase.couchbase-server cert

also see:  http://review.couchbase.org/#/c/30422/

Change-Id: Icfe2380d13d7992d019739b45022ce84b1c0d0ef
Reviewed-on: http://review.couchbase.org/30423
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>