title: React Native - NSNumber cannot be converted to NSString
body: <p>Below is part of my react component.  I have a props named daysUntil coming into this component which contains a number.  In this example it is being pass the number 0 which results in the fontWeight function returning 700</p>
  
  <pre><code>render: function() {
      return (
        &lt;Text style={this.style()}&gt;
         {this.props.day}
        &lt;/Text&gt;
      )
    },
    style: function() {
      return {
        fontWeight: this.fontWeight()
      }
    },
    fontWeight: function() {
      var weight = 7 - this.props.daysUntil;
      return weight * 100;
    }
  </code></pre>
  
  <p>I get the following error:</p>
  
  <blockquote>
    <p>JSON value '700' of type NSNumber cannot be converted to NSSTring.</p>
  </blockquote>
  
  <p>I'm assuming this is because font-weight expects the value to be in string format.  What's the proper fix for this?</p>
  
  <p>Thank you in advance!</p>