Adding CentOS 5.8 builddocker

Change-Id: I0026bf8d76d1010895e0f9c72047cfb6d23318c2
Reviewed-on: http://review.couchbase.org/40721
Reviewed-by: Chris Hillery <ceej@couchbase.com>
Tested-by: Chris Hillery <ceej@couchbase.com>