How to set IconicsDrawable to bold?
Hi Mike,

I'm using `IconicsDrawable` to set an icon for an `ImageView`. Currently I set the icon font to bold by...:

```java
GoogleMaterial.Icon add = GoogleMaterial.Icon.gmd_add;
imgView.setImageDrawable(new IconicsDrawable(img.getContext(), add)
       .typeface(Typeface.create(add.getTypeface().getTypeface(getContext()), Typeface.BOLD))
       .sizeDp(20).color(Color.WHITE).backgroundColor(Color.GRAY).paddingDp(5));
```
Is there a more optimal way?
