* Create Redisable

* Use #redis instead of Redis.current

* Delete trends_controller.rb

* Update routes.rb

* Update trending_tags.rb

* Update index.js

* Update index.js

* Update search_results.js

* Update async-components.js

* Update index.js

* Delete trends.js

* Delete trends.js

* Delete trends_container.js

* Delete trends.js

* Update search_results.js

* Update search_results_container.js

* Track trending tags

- Half-life of 1 day
- Historical usage in daily buckets (last 7 days stored)
- GET /api/v1/trends

Fix #271

* Add trends to web UI

* Don't render compose form on search route, adjust search results header

* Disqualify tag from trends if it's in disallowed hashtags setting

* Count distinct accounts using tag, ignore silenced accounts