Image view (XML) doesn't work, cannot set icon via app:ico_icon 
Hi,
I have just started to use the library in my project. I have followed all the steps described in the README section to include the google material icons and use them as icons sources for ImageView. Anyway it seems that it doesn't work at all. Here my code:

``` java
 <ImageView
        xmlns:app="http://schemas.android.com/apk/res-auto"
        android:layout_width="48dp"
        android:layout_height="48dp"
        app:ico_icon="gmd-location-on"
        app:ico_color="@android:color/black"
        app:ico_size="48dp"/>
```

In my activity:

``` java
    /**
     * Define IconicsLayoutInflater to enable automatic xml icons detection
     * @param newBase
     */
    @Override
    protected void attachBaseContext(Context newBase) {
        super.attachBaseContext(IconicsContextWrapper.wrap(newBase));
    }
```

My gradle:

```
    compile 'com.mikepenz:iconics-core:2.5.11@aar'
    //Icons
    // Google Material Icons
    compile 'com.mikepenz:google-material-typeface:2.2.0.1@aar'
    //Font awesome
    compile 'com.mikepenz:fontawesome-typeface:4.6.0.1@aar'
    //Material icons
    compile 'com.mikepenz:material-design-iconic-typeface:2.2.0.1@aar'
```

Do I miss something?
