Add Itunes::Track#update_attributes

# Change
- Add `Itunes::Track#update_attributes`
- Update version to `0.0.3`

## Example
```ruby
track = Itunes::Track.find_by(name: 'Hello, Goodbye').first
track.name
=> "Hello, Goodbye"

track = track.update_attributes(name: 'Hello, Goodbye!')
track.name
=> "Hello, Goodbye!"
```