Use unparsed_uri to build Sec-WebSocket-Location header.

Release note: Changed Sec-WebSocket-Location to include the query part.

BUG= https://code.google.com/p/pywebsocket/issues/detail?id=68
Review URL: https://codereview.appspot.com/7568046

git-svn-id: http://pywebsocket.googlecode.com/svn/trunk@741 4ff78f4a-9131-11de-b045-6380ec9940d4