Added more diagnostic information from Server to Client when using SPARQL Endpoint

Hi Kal,

I've got another one for you! 

I found it frustrating when using the Windows Service that it didn't return the error information when the client issued a Bad Request over HTTP. I've changed the server to return the detailed error information from the SPARQL parser in the response body, and I've changed the Polaris client to show this information in the stack trace (as the message in the Brightstar client exception). This is useful because you get really good errors back from the parser.

I'm a little worried that these changes aren't in keeping with the way you want the application written or error handling managed, so no worries if you don't want the pull request!

Regards,

Dan