upgrade Savon to 2.3.0 without any problems at all

@Simbul @dawid-sklodowski @pendletons please sign off

A hack needed to be added to get the ```attributes!``` key to work and add the extra attributes to each of the objects in the message.
that's the way to do it if you want to add the attribute to each individual object.
done by this [gem](https://github.com/savonrb/gyoku)