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)


Why do we need to check the key as well as the derivation operator?

Is dc.key every going to be different from just key?