Use concat not lodash union for patientData

Use `Array.prototype.concat` vs. `_.union` to merge device data and notes on client-side.

Quick check: a dataset that used to take ~28 sec to fetch and process now takes ~8 sec.

Credit to where it's due (I didn't do anything really, just change 1 line of code):

- thanks @cheddar for finding the bottleneck
- thanks @jebeck for pointing out that it was silly to use `_.union` there which checks for duplicates

BEFORE:
![screen shot 2014-07-14 at 3 38 07 pm](https://cloud.githubusercontent.com/assets/1306536/3576470/58aee152-0b92-11e4-9453-de133b935427.png)

AFTER:
![screen shot 2014-07-14 at 3 50 27 pm](https://cloud.githubusercontent.com/assets/1306536/3576471/5f128634-0b92-11e4-8564-008887536a42.png)