added explicit permission for external storage

Example/android/app/src/main/AndroidManifest.xml

     <uses-permission android:name="android.permission.CAMERA"/>
     <uses-permission android:name="android.permission.RECORD_AUDIO"/>
     <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>
     <uses-permission android:name="android.permission.READ_CONTACTS"/>
     <uses-permission android:name="android.permission.READ_CALENDAR"/>
 

ReactNativePermissions.js

 		'contacts',
 		'event',
 		'photo',
+		'storage'
 	]
 }
 

android/src/main/java/com/joshblour/reactnativepermissions/ReactNativePermissionsModule.java

     MICROPHONE,
     CONTACTS,
     EVENT,
+    STORAGE,
     PHOTO;
   }
 
         return Manifest.permission.READ_CONTACTS;
       case EVENT:
         return Manifest.permission.READ_CALENDAR;
+      case STORAGE:
       case PHOTO:
         return Manifest.permission.READ_EXTERNAL_STORAGE;
       default: