[Enhancement] Delete media after "x" days (#160)

* [Enhancement] Adds ability to stop media from re-downloading (#159)

* Added column

* Added methods for ignoring media items from future download

* Added new deletion options to controller and UI

* Added controller actions and UI for editing a media item

* Added column to sources

* Added retention period to form

* [WIP] getting retention methods in place

* Hooked up retention worker

* Added column and UI to prevent automatic deletion

* Docs

* Removed unused backfill worker

* Added edit links to media item tabs on source view

* Clarified form wording

* Form wording (again)

lib/pinchflat_web/router.ex

@@ -32,7 +32,7 @@ defmodule PinchflatWeb.Router do
     resources "/search", Searches.SearchController, only: [:show], singleton: true
 
     resources "/sources", Sources.SourceController do
-      resources "/media", MediaItems.MediaItemController, only: [:show, :delete]
+      resources "/media", MediaItems.MediaItemController, only: [:show, :edit, :update, :delete]
     end
   end