CBLT-198:  SYNCGATE_VERSION now n.n-mmmm, in native installers instead of zipfiles

Change-Id: Ibfccbe44ea43015514e2ff47fb5c7f63124d113b
Reviewed-on: http://review.couchbase.org/34198
Reviewed-by: Philip Labee <philip@couchbase.com>
Tested-by: Philip Labee <philip@couchbase.com>