Notifications: Fix issues with use of computeTotal query parameter

[scblack321]

Received report:

Interesting bit of information. For /apps, /systems, /jobs. If computeTotal=True is set, limit cannot be 0 or totalCount is returned as 0. Limit of 1+ works. I imagine limit==0 probably skips logic.

Also if computeTotal=True and I have 0 jobs the return gives metadeta.computeTotal=-1 rather than 0, which is a bit unexpected. I've dealt with both though, so no need for changes on my end.