Rework the script to deal with non-presence of bundler from the get go

git-svn-id: https://svn.apache.org/repos/asf/buildr/trunk@1531464 13f79535-47bb-0310-9956-ffa450edef68
Add a retry for an intermittently failing test

git-svn-id: https://svn.apache.org/repos/asf/buildr/trunk@1531465 13f79535-47bb-0310-9956-ffa450edef68