N3ssi3: Overwrite Design by AttributeSet, simular to PRODUCT_TYPE_bundle

In layout.xml you already have the opportunity to change the layout by Product_Type and Product_Id.
I added the same functionality for AttributeSets.

You can name your AttributeSet as you like: in my case "Shirts T".
Since there are no spaces allowed in xml nodes, all the spaces and other characters are being replaced by underscores.
So in my case it would look like this:
```
    <PRODUCT_ATTRIBUTE_SET_NAME_Shirts_T>
        <reference name="head">
            <action method="setTitle" translate="title" module="catalog"><title>PRODUCT_ATTRIBUTE_SET_NAME_Shirts_T</title></action>
        </reference>
    </PRODUCT_ATTRIBUTE_SET_NAME_Shirts_T>
```

````
:warning: As a Designer/Developer you should restrict your customers Admin account, so he won't change your AttributeSetNames
```