title: React Navigation Reset Can add parameters?
body: <p>I am still new to react navigation.
  I wish to reset the route information after login successfully. However there is some parameters like login information I wish to pass to the main page. </p>
  
  <pre><code>import { NavigationActions } from 'react-navigation'
  
  const resetAction = NavigationActions.reset({
    index: 0,
    actions: [
          NavigationActions.navigate({ routeName: 'Profile',
                  params:{user:this.state.username}})
        ]
    })
      this.props.navigation.dispatch(resetAction)
  </code></pre>
  
  <p>In the Profile page, I want to get access to the params, so I use this:</p>
  
  <pre><code>constructor(props){
  super(props)
  this.state = { username: this.props.navigation.state.params.user, 
    }
  </code></pre>
  
  <p>but I received: <strong>undefined is not an object (evaluating '_this.props.navigation.state.params.user')</strong> in the Console log.
  May I know how should I get the parameters? Thank you</p>