Add ttl option to parse_feed

Cache time to live can be specified in the Podcast#parse_feed method.

the feed:update task uses a 0 time to live, which will skip the cache
Addinb gemfile.lock
Add category label to podcast#show
Move list of podcast template from subscriptions to podcasts/index
Add category show ember view

Some of the code in this commit is really hacky. I don't like that ember
pluralizes 'category' to 'categorys'.
Commiting backup podcast list
Add podcast index sorted by subscription count.
List categories next to podcasts
Merge branch 'categoriy-ui'
Fix subscriptions_count migration
Encode search terms to prevent errors
Merge branch 'search'
Fix controller test
Update existing tests and factories to support episodes
QueueManager can add episodes at the beginning or end of the queue
Finish QueueManager object
Removed logger from feed cache
Improve QueueManager Documentation
Refactor: Add do_with_rebase_retry functio.

Extracted rebase and retry logic to a function.
Ignore the added test, it was previously left commented out.
Add `add_before` and `add_after` methods to QueueManager