public int getContentView() {
        return R.layout.activity_pin_code;
    }
Gets the resource id to the {@link View} to be set with {@link #setContentView(int)}.
The custom layout must include the following:
- {@link TextView} with an id of pin_code_step_textview
- {@link TextView} with an id of pin_code_forgot_textview
- {@link PinCodeRoundView} with an id of pin_code_round_view
- {@link KeyboardView} with an id of pin_code_keyboard_view

@return the resource id to the {@link View}
lib/src/main/java/com/github/omadahealth/lollipin/lib/managers/AppLockActivity.java