Overhaul Production Queue

**Issue by [chaorace](https://github.com/chaorace)**
_Saturday May 20, 2017 at 21:52 GMT_
_Originally opened as https://github.com/CQUI-Org/cqui/issues/537_

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We've been talking about it for a long time, so I thought I'd finally make it official. We're _eventually_ overhauling the PQ, probably not for some time though. Doing this will resolve #53 #75

While reimplementing, we should also tackle enhancements #40 #42 #58 #86 and #93

Start by reviewing the current Production Queue implementation and the related issues #53, #75, #40, #42, #58, #86, and #93. No source file, test, entry point, or acceptance criteria is named, so the intended overhaul and definition of done need to be established before implementation.

Written by the indexing model from the issue text.