* Add examples of view display 
* view helpers?
* Chaining stages with string (to avoid having to load stages before pipeline)
* Adapter for other persistence frameworks (ActiveModel?)
* Adapter for other background processing mechanisms (currently relying on dj's auto-retry)
* Max attempts on pipeline (or stage)

Think more about:
- Repeated code on status handling on pipeline instance/pipeline stage
- Composite for nesting stages? (is that useful?)
- Can I cancel a stage/pipeline that's in progress?
- Pausing a stage?