Fixed bug with Android < 23

lib/permissions.android.js

   microphone: PermissionsAndroid.PERMISSIONS.RECORD_AUDIO,
   contacts: PermissionsAndroid.PERMISSIONS.READ_CONTACTS,
   event: PermissionsAndroid.PERMISSIONS.READ_CALENDAR,
-  storage: PermissionsAndroid.PERMISSIONS.READ_EXTERNAL_STORAGE,
-  photo: PermissionsAndroid.PERMISSIONS.READ_EXTERNAL_STORAGE,
+  storage: PermissionsAndroid.PERMISSIONS.WRITE_EXTERNAL_STORAGE,
+  photo: PermissionsAndroid.PERMISSIONS.WRITE_EXTERNAL_STORAGE,
   callPhone: PermissionsAndroid.PERMISSIONS.CALL_PHONE,
   readSms: PermissionsAndroid.PERMISSIONS.READ_SMS,
   receiveSms: PermissionsAndroid.PERMISSIONS.RECEIVE_SMS,