Corrected screenId to screenID (#596)

* Added default testId to registered components

* Added default testID to registered components

* Corrected screenId to screenID

src/Navigation.js

 
       render() {
         return (
-          <InternalComponent testID={screenId} navigator={this.navigator} {...this.state.internalProps} />
+          <InternalComponent testID={screenID} navigator={this.navigator} {...this.state.internalProps} />
         );
       }
     };
       render() {
         return (
           <Provider store={store}>
-            <InternalComponent testID={screenId} navigator={this.navigator} {...this.state.internalProps} />
+            <InternalComponent testID={screenID} navigator={this.navigator} {...this.state.internalProps} />
           </Provider>
         );
       }