Add enable/disable swipe feature

I needed to disable the swipe in certain occasions and re-enable it in others. I inferred that that was the job of the method setEnabled() given its description::

> Enables or disables (pauses or resumes) watching for swipe-to-dismiss gestures.

However it doesn't work as expected because of this method in AbsListView.OnScrollListener():

    public void onScrollStateChanged(AbsListView absListView, int scrollState) {
        setEnabled(scrollState != AbsListView.OnScrollListener.SCROLL_STATE_TOUCH_SCROLL);
    } 

So I decided to implement it using a new method and property.