Extend version regex to support four-digit versions

Change-Id: I02c78db5b1390984307e1075fada6fe5823a962a
Reviewed-on: http://review.couchbase.org/42332
Reviewed-by: Jessica Liu <jessica@couchbase.com>
Reviewed-by: Traun Leyden <tleyden@couchbase.com>
Tested-by: Traun Leyden <tleyden@couchbase.com>