Use static constants instead of strings when referring to View Manage…

…rs and Native Modules

Summary: Using strings to refer to Native Modules and View Managers in ReactPackages are prone to error. The compiler replaces the constants with the actual strings anyway, so using constants gives us  better type safety

Reviewed By: achen1

Differential Revision: D12843649

fbshipit-source-id: 7a7c6c854c8689193f40df92dc8426a3b37f82c8

ReactSliderManager.java

@@ -38,7 +38,7 @@ public class ReactSliderManager extends SimpleViewManager<ReactSlider> {
 
   private static final int STYLE = android.R.attr.seekBarStyle;
 
-  private static final String REACT_CLASS = "RCTSlider";
+  public static final String REACT_CLASS = "RCTSlider";
 
   static class ReactSliderShadowNode extends LayoutShadowNode implements
       YogaMeasureFunction {