Auphonic: hide "choose production" item on select
don't pass `redirect=no` parameter to feed URLs
web player: remove state → avoid bugs
fix caching bug

If templates are rendered differently in different contexts, that
context must be part of the cache key. In this case, `is_feed()` was
missing.

issue #448
flush rewrite rules after migrations
flush rewrite rules on next release
purge cache on next release
purge cache after migrations
fix redirection ui bug

… by resetting item indices before rendering