Source: Remove ignore_etags option

This is never used anywhere else apart from the testsuite. Instead
of ignoring etags we should instead not save them if the feed does
not return 200 or 304. See #64.

podcasts-downloader/src/downloader.rs

@@ -253,7 +253,7 @@ mod tests {
         // Copy it's id
         let sid = source.id();
         // Convert Source it into a future Feed and index it
-        pipeline::run(vec![source], true).unwrap();
+        pipeline::run(vec![source]).unwrap();
 
         // Get the Podcast
         let pd = dbqueries::get_podcast_from_source_id(sid).unwrap().into();