Asynchronous script execution

Asynchronous methods for working with scripts:

• Start calculation
  gateway_url/ipm/projects/{projectId}/python/start_async?topic=python_start_test

(returns the ID of the started script)

• Stop calculation
  gateway_url/ipm/projects/{projectId}/python/stop_async?topic=python_start_test&userCalcId={calcId}
• Calculation status
  gateway_url/ipm/projects/{projectId}/python/exists_async?userCalcId={calcId}