Incorrect output on some submission failures

[rbx]

When Submit is called multiple times with the same agent group, and any after the first submissions fail, the submission log can contain misleading info such as:

Number of agents (3) for group online is less than requested (1), and no nMin is defined.

[rbx]

Somewhat related problem: when nMin is given on submit, and submit is called multiple times with a lower number of required agents, then a single submission will be malformed, because for it minAgents > requiredAgents.

[rbx]

Possible solution: submit only once per agent group.