function diff (array1, array2) {
    return array1.filter(function (i) {
        return array2.indexOf(i) < 0;
    });
}
Add phonegap.js DEPRECATION warning.

Display DEPRECATION warning when the app references phonegap.js

Options:

  - `options` {Object} is identical to the Cordova command input.
  - [`callback`] {Function} is triggered after executing the command.
    - `e` {Error} is null unless there is an error.