Improve handling of query timeouts.
1/ Send dev/debugging explanation after stopping sending streamed results 
2/ Copy result set early for text output to generate the right
   HTTP status code - do before starting to format results.
   


git-svn-id: https://svn.apache.org/repos/asf/jena/trunk@1469055 13f79535-47bb-0310-9956-ffa450edef68