Dashboard: invalid representation of action execution result

[Renat Akhmerov]

When we're interpreting a result of an action execution we need to keep in mind that the form

{
    "result": null
}

is only a way how we store the result in DB.

The real action result in this case is "null" (actually should be None).

This issue is reported for the Dashboard but we need to investigate it more thoroughly. I guess we just might want to change what Mistral API gives as an action result.

In the Dashboard it appears in "Action Execution Details" view.