Specification defect - No default environment onExit action timeouts

[jusiskin]

This discussion post is to raise awareness of a defect in the OpenJobDescription specification. In summary, there is no default timeout for environment exit session actions. This is problematic since OpenJobDescription sessions should by default be able to be ended in a reasonable bound time duration for use-cases like canceling a job that could be stuck.

See #70 to track/discuss this issue and the resolution path.

[jusiskin]

Providing an update on this defect here.

To address the defect, the specification has been updated in the following places:

1. <EnvironmentActions> definition
2. <Action> definition

With the specification updated, the next action is to update the openjd-sessions Python library to apply this new default. I've created OpenJobDescription/openjd-sessions-for-python#212 to track this effort.