title: How to set defaultValue for react-select Async and not reset when onBlur at v2.0.0?
body: <p>I try to apply react-select to create async selection like <a href="https://jedwatson.github.io/react-select/" rel="noreferrer">the demo</a>,
  And want to add default value for the input.<br>
  As below, the default value will be clear when onBlur because onBlur will default trigger handleInputChange event with empty value.<br>
  I guess this might case by some default setting like 'onBlurResetsInput',
  but 'onBlurResetsInput' props has be removed at <a href="https://deploy-preview-2289--react-select.netlify.com/upgrade-guide" rel="noreferrer">v2.0.0</a>.
  So want to know how to prevent onBlur reset, thanks.</p>
  
  <pre><code>import Async from 'react-select/lib/Async';
  export class AsyncSelect extends React.PureComponent {
    state = {
      inputValue: this.props.defaultValue,
    }
  
    handleInputChange = (value) =&gt; {
        this.setState({
          inputValue: value,
        });
        this.props.syncOptions(value);
    }
  
    render() {
      return (
          &lt;Async
            inputValue={this.state.inputValue}
            onInputChange={this.handleInputChange}
            options={this.props.options}
            onChange={(option) =&gt; this.props.selectOption(option.value)}
          /&gt;
      );
    }
  }
  </code></pre>