title: How to format a Swift 3 nsmeasurement string to at most 2 decimal places after conversion?
body: <p>I would like to know how to round nsmeasurement after conversion from a unitmass. From Kilograms to Pounds for example and rounding to the 2nd decimal place instead of giving me the exact.</p>
  
  <pre><code> var x = Measurement(value:19, unit: UnitMass.kilograms)
   x.convert(to:UnitMass.Pounds)
   x.description // "41.8878639834918 lb"
  </code></pre>
  
  <p>I'd like it to be 41.89 </p>