Replace React.createClass with create-react-class

Summary:
This replaces all uses of `React.createClass` with `createReactClass` from the `create-react-class` package, attempting to match use of `var` and `const` according to local style.

Fixes #14620
Refs #14712
Closes facebook/react-native#14729

Differential Revision: D5321810

Pulled By: hramos

fbshipit-source-id: ae7b40640b2773fd89c3fb727ec87f688bebf585

Slider.js

@@ -21,6 +21,7 @@ var PropTypes = require('prop-types');
 var StyleSheet = require('StyleSheet');
 var ViewPropTypes = require('ViewPropTypes');
 
+var createReactClass = require('create-react-class');
 var requireNativeComponent = require('requireNativeComponent');
 
 type Event = Object;
@@ -29,7 +30,8 @@ type Event = Object;
  * A component used to select a single value from a range of values.
  */
 // $FlowFixMe(>=0.41.0)
-var Slider = React.createClass({
+var Slider = createReactClass({
+  displayName: 'Slider',
   mixins: [NativeMethodsMixin],
 
   propTypes: {