Step support for SliderIOS

Summary: Add step support to SliderIOS
Closes https://github.com/facebook/react-native/pull/3746

Reviewed By: svcscm

Differential Revision: D2595360

Pulled By: nicklockwood

fb-gh-sync-id: 4adf8bcdf46c709776d779244ba3de2b40eb27d6

Libraries/Components/SliderIOS/SliderIOS.ios.js

@@ -41,6 +41,13 @@ var SliderIOS = React.createClass({
      */
     value: PropTypes.number,
 
+    /**
+     * Step value of the slider. The value should be
+     * between 0 and (maximumValue - minimumValue).
+     * Default value is 0.
+     */
+    step: PropTypes.number,
+
     /**
      * Initial minimum value of the slider. Default value is 0.
      */
@@ -103,6 +110,7 @@ var SliderIOS = React.createClass({
       <RCTSlider
         style={[styles.slider, this.props.style]}
         value={this.props.value}
+        step={this.props.step}
         maximumValue={this.props.maximumValue}
         minimumValue={this.props.minimumValue}
         minimumTrackTintColor={this.props.minimumTrackTintColor}