Correct job RunTime if requeued from suspend state

Without this patch, the job's RunTime includes its RunTime from
before it's prior suspend (i.e. the job's full RunTime rather than
just the RunTime of the requeued job).
Reset job priority on manual resume

If a job is explicitly suspended, its priority is set to zero.
This resets the priority when requeued and also documents that
if the job is requeued (e.g. due to a node failure), then it
is placed in a held state.