FloatingActionButton icon size too small
Hi mike

I m using your lib to place an icon on a FloatingActionButton like this 

``` java
fab.setImageDrawable(new IconicsDrawable(this, GoogleMaterial.Icon.gmd_share)
.color(Color.WHITE).sizeDp(16));
```

but the icon is too small.. even when i increase the sizeDp value.

the xml of fab has layout width and height set to 30dp. 
