Interpret Runtime's 'Cancelled - Ran too long' state as Cancelled.

[renier]

Interpret Runtime's 'Cancelled - Ran too long' state as Cancelled.

Docs will be updated soon to reflect this new state in the API. This is a workaround until the cancelled state has a reason value (implies state becomes a tuple of status, reason).

[jyu00]

This perhaps would be better mapped to Error instead of Cancelled, since the latter implies it's cancelled by the user. We should also have a new error_message() method to tell the user why it failed.