v0.2.0

Major changes:

• add_media_to_item() now lets you supply a metadata payload so you can add whatever properties you want to the media file. You can also specify a template and resource class. This should be backwards compatible.
• If you supply a template id but not a resource class id to either add_media_to_item() or add_item() they will now apply the template's default resource class (if it has one) to the item. If you supply a resource class id, your value will override the template's value.