How to add pressed state for IconicsDrawable set as Compound Drawable
Hi Mike,
is it possible to change iconics drawable color while it's in pressed state? I was unsuccessful while trying to use StateListDrawable - it has never shown. Any idea how I should proceed? 

In my example I am setting facebook icon as "left drawable" of "Button" element. Not sure how to change iconics drawable color while it's in pressed state (button text gets changed from white to blue by states defined in @color/state_button.xml file).

Thanks for you help.

```
        IconicsDrawable fbDrawable = new IconicsDrawable(getActivity())
                .icon(FontAwesome.Icon.faw_facebook_f)
                .color(getResources().getColor(R.color.primary_color))
                .sizeDp(24);
        fbDrawable.setBounds(0, 0, 60, 60);
        mShareFacebookBtn.setCompoundDrawables(fbDrawable, null, null, null);
```
