title: How to set navigation params properly
body: <p>I use react-navigation for navigation in my app. I have some modal view (<em>SomeComponent</em>) and I wanna set custom title during presenting animation. The problem is that title is changing but after presenting animation is finished.</p>
  
  <p>I've tried set params in other component lifecycle callback but it didn't work. 
  <em>I don't want to set this parameter with navigate function</em> because I don't have full data to set it.</p>
  
  <pre><code>class SomeComponent extends React.Component {
      static navigationOptions = ({ navigation }) =&gt; {
          return {
              title: navigation.getParam("customTitle"),
          }
      }
      componentDidMount() {
          this.props.navigation.setParams({ customTitle: "Some custom title" })
      } 
  }
  </code></pre>
  
  <p>I wanna set title before animation is finished.</p>