Make it non-fatal when the recommendation service errors out

Render a nice warning and log the exception but render the rest of the
page, because recommendations are never primary content on these pages.
Install rails-behaviors with Bower since the gem was pulled
Switch to Ruby 2.1.3 and Unicorn server
Bump assets libraries
Bump HTTP client libraries
Enable rack-cache via memcached in production
Fix assets precompile on Heroku

https://devcenter.heroku.com/articles/rails-asset-pipeline#troubleshooting
Fix crash in TwinAdapter
Add rails_12factor for Heroku