Couple XBMC Metadata fixes

Fixed: Actor URL for XBMC Metadata
Fixed: Incorrectly storing season images for XBMC metadata
(cherry picked from commit 5b2c3b88c0fdf002bb46a45e85c2f5066cc84877)
Download clients now use thingy provider
Validation, settings UI cleanup and different settings models, oh my

New: Download client UI matches other settings
Fixed: Prevent drone factory folder from being set to invalid paths/root path for series
Fixed: Switching pages in settings will not hide changes
Fixed: Test download clients
Fixed: Settings are validated before saving
Fixed root folder integration test
Reordered migrations after rebase