Does the IconicsLayoutInflater work with android.support.v7.widget.AppCompatButton buttons?
I've been incorporating your library into my project for the past couple weeks successfully, thank you for your efforts!

I have an xml layout which I've a/b tested with android.support.v7.widget.AppCompatButton and just a plain Button:

```
        <android.support.v7.widget.AppCompatButton xmlns:app="http://schemas.android.com/apk/res-auto"
            android:id="@+id/buttonSignup"
            style="@style/Sugar.Button.Tall"
            android:layout_width="match_parent"
            android:layout_marginTop="@dimen/control_vertical_margin_large"
            android:text="@string/{faw-envelope} Sign up with Email"
            android:textColor="@color/sugar_secondary"
            app:backgroundTint="@color/button_white_tint" />
```

I am using the IconicsLayoutInflater:

```
LayoutInflaterCompat.setFactory(getLayoutInflater(), new IconicsLayoutInflater(getDelegate()));
```

When using just a plain `Button`, the font awesome icon appears, when I use the `AppCompatButton`, I get only `{faw-envelope}`

Any ideas? Should the icons be detected with an AppCompatButton?