title: react/typescript: Parameter 'props' implicitly has an 'any' type error
body: <p>When I try this sample code from react-bootstrap, I keep getting errors such as " Parameter 'context' implicitly has an 'any' type; "Property 'value' does not exist on type 'Readonly&lt;{}>'." </p>
  
  <p>in form.tsx:</p>
  
  <pre><code>class FormExample extends React.Component {
    constructor(props, context) {
      super(props, context);
  
      this.handleChange = this.handleChange.bind(this);
  
      this.state = {
        value: ''
      };
    }
  
    getValidationState() {
      const length = this.state.value.length;
      if (length &gt; 10) return 'success';
      else if (length &gt; 5) return 'warning';
      else if (length &gt; 0) return 'error';
      return null;
    }
  
    handleChange(e) {
      this.setState({ value: e.target.value });
    }
  
    render() {
      return (
        &lt;form&gt;
          &lt;FormGroup
            controlId="formBasicText"
            validationState={this.getValidationState()}
          &gt;
            &lt;ControlLabel&gt;Working example with validation&lt;/ControlLabel&gt;
            &lt;FormControl
              type="text"
              value={this.state.value}
              placeholder="Enter text"
              onChange={this.handleChange}
            /&gt;
            &lt;FormControl.Feedback /&gt;
            &lt;HelpBlock&gt;Validation is based on string length.&lt;/HelpBlock&gt;
          &lt;/FormGroup&gt;
        &lt;/form&gt;
      );
    }
  }
  
  export default FormExample;
  </code></pre>
  
  <p>in Jumbo.tsx:</p>
  
  <pre><code>const Jumbo = () =&gt; (
     &lt;FormExample /&gt;
  );
  </code></pre>