Add space_id to instance now that cc_ng is sending it.

   * this is needed for log annotation
   * being handed the space_id is more efficent that looking it up downstream

Signed-off-by: Stephan Hagemann <stephan@pivotallabs.com>
nest space_id under tags for instance

Signed-off-by: Alex Jackson <ajackson@pivotallabs.com>
Merge pull request #37 from cloudfoundry/space_guid_on_dea_message

Add space_id to instance now that cc_ng is sending it.