oq-engine-server: Implement 'list calc results' views

[Lars Butler]

URL:
  /vX/calc/hazard|risk/:calc_id/results
Response:
  List of {id, name, type, url} objects, as JSON.
  Example:
    [{'id': 1, 'name': 'mean curves PGA', 'type': 'hazard_curve', 'url': 'http://www.openquake.org/api/vX/calc/hazard/result/1'}, {'id': 2, 'name': 'mean curves SA(0.1)', 'type': 'hazard_curve', 'url': 'http://www.openquake.org/api/vX/calc/hazard/result/2'}, {'id': 3, 'name': 'mean curves SA(0.2)', 'type': 'hazard_curve', 'url': 'http://www.openquake.org/api/vX/calc/hazard/result/3'}]

  The urls in the response can be used to stream the result as XML/GeoJSON.

Open issue: Since some results (at the time of this writing, hazard_maps and loss_maps only) are available in XML or GeoJSON. The actual result download API endpoint (http://www.openquake.org/api/vX/calc/hazard/result/3) may require an 'export_type' parameter or something.

[Lars Butler (lars-butler)]

Pull request: https://github.com/gem/oq-engine-server/pull/4