Allow user to delete their podcast

[andrewmarklloyd]

In the settings for a podcast, there should be an option to delete the podcast. There should be ample warnings letting the user know the ramifications:

• all website data will be removed
• all episodes will be deleted from storage and will not be retrievable
• the RSS feed will be removed
• the podcast will be removed from iTunes and Google Play

There should be a confirmation where the user must type in the name of the podcast to ensure the podcast is not deleted on accident.

We should consider giving the option to export all of the data.

This could be split up into separate backend and frontend issues.