Prevent false-highlighting-bubbling for specific occurrences within Unions

### Story ###
- https://www.pivotaltracker.com/story/show/78230864

### Notes ###
- only consider unique occurrences when building specificsRationale
- extend ```orCounts``` to consider grouping data criteria representing Unions

### Screenshots ###
- undesired false-bubbling
  - ![screen shot 2014-09-10 at 9 03 39 am](https://cloud.githubusercontent.com/assets/456952/4217738/0638fa26-38eb-11e4-93e8-68e8f08b3b3d.png)
- fixed false-bubbling
  - ![screen shot 2014-09-10 at 9 03 57 am](https://cloud.githubusercontent.com/assets/456952/4217737/063645a6-38eb-11e4-9416-e0502a8df015.png)


I had into issues with a jasmine [spec](https://github.com/projecttacoma/bonnie/blob/master/spec/javascripts/models/result.spec.js.coffee#L13) when I was only checking for the ```derivation_operator``` (other groupings, typically with temporal references also have a UNION derivation_operator, so I opted to exclude them from this change).

I think in this context ```key``` will be the same value as ```dc.key```; would it be cleaner to just replace all usage of ```dc.key``` with key?