RSS support

[sophiebremer]

Is your feature request related to a problem? Please describe.
Fetch and read RSS channels and their items from an URL.

Describe the solution you'd like
A RSS class should cover the required interface to give access to:

• Copyright
• CDATA Image
• Description
• Enclosure Media
• Image
• iTunes Category
• Link
• Publishing Date
• Title
• General Unique ID

Describe alternatives you've considered
Atom is an alternative to RSS, but nowadays more exotic.

Additional context

• Basic overview over RSS structure is shown at Wikipedia.
• A more comprehensive overview can be found at Harvard.
• This should support Podcasts as described in Apple's Podcast Requirements and iTunes Connect.