MB-100: print buildout output to stdout

Change-Id: I43ca0b8295cefa4aafc9afee70e4b3cf633ece60
Reviewed-on: http://review.couchbase.org/23705
Reviewed-by: Pavel Paulau <pavel.paulau@gmail.com>
Tested-by: Pavel Paulau <pavel.paulau@gmail.com>