title: How to retrieve a string in ReactIntl 2.0 without using FormattedMessage
body: <p>Please correct me if I am wrong, FormattedMessage in ReactIntl returns a string wrapped by span tags. In ReactIntl 1.2, we have the option to use <code>this.getIntlMessage('key')</code> to get only the string part. </p>
  
  <p>Here is my question: Is there an equivalent of that in ReactIntl 2.0? I am aware that the string can be obtained by using the Function-As-Child pattern in FormattedMessage as </p>
  
  <pre><code>&lt;FormattedMessage id="placeholder"&gt;
      {(formattedValue)=&gt;(
          &lt;MyComponent ref="mycomponent" placeholder={formattedValue}/&gt;
      )}
  &lt;/FormattedMessage&gt;
  </code></pre>
  
  <p>However, it messes up the 'ref' in my component and I can't access to the component using <code>this.refs.mycomponent</code> any more.  </p>