Parse Version query parameter for XML namespace

 - Base response off http://queue.amazonaws.com/doc/%s/ where %s
   is supplied by the Version= query parameter
   Default to 2012-11-05, but other standard values are 2011-10-01,
   and 2009-02-01
Merge pull request #4 from Iristyle/sqs-version

Parse Version query parameter for XML namespace