improve mechanism inside invocation rule
improve mechanism inside invocation rule

This improves the mechanism inside the invocation rule to check if all tasks are
completed.

Some temp variables are removed away, and it should check the task status in each loop,
to return the result when it is the right condition.

This enhance readability and the performance a little.

fission/fission-workflows,fission/fission-workflows,fission/fission-workflows,fission/fission-workflows