Fix duplicate Expected Value inputs in Patient Builder view

#### Story ####
- https://www.pivotaltracker.com/story/show/69469804

#### Notes ####
- expected values were updated to support <code>OBSERV_UNIT</code> for CV measures, but remained erroneous
- the fix involved only setting an <code>OBSERV_UNIT</code> for CV measures, and passing a <code>{silent:true}</code> when doing so ( taken from the response to this familiar issue: https://github.com/walmartlabs/thorax/issues/300 )

#### Screenshot ####
- duplicate expected values in patient builder elements (expected-0, expected-1)
  - ![screen shot 2014-05-12 at 10 54 23 am](https://cloud.githubusercontent.com/assets/456952/2946848/e723785a-d9ef-11e3-9678-3f62e9439cc8.png)