Search itunes and fyyd on a new page.

discovery: search itunes and fyyd on a new page.

This replaces the add button popover, which had horrible usability on screen reader and mobile.

Also the new Subscribe action will auto remove sources that failed to import a Show.

Progress:

• test url import still works
• add test cases for podcasts_data::discovery

Fixes #244 (closed) #247 (closed) and #94 (closed)