Upgrade newrelic gem

* Specified version gives alert that newrelic "requires a security update for
  their Postgres explain plan support"
* Gem version was last set in July 2013: https://github.com/thoughtbot/suspenders/commit/8f133d2bd0f67097495a9c120f724754ef7b0285#diff-2b85b2e387999d51ca372ef132583e80
Improve memory of app on Heroku w/ New Relic

* Help avoid R14 (Memory quota exceeded) errors.
  http://forum.upcase.com/t/how-to-free-up-swap-space-heroku/3017
* Refactor away some duplication.