Add Google Analytics and New Relic Monitoring

 * Add google-analytics-rails gem
 * Set GA.tracker from environment variable in production environment
 * Render GA tracking code in head of all pages via application layout. Move app JavaScripts to the end of the page.
 * Add new_relic gem
 * Add downloaded newrelic.yml
 * Update newrelic.yml from heroku example
Merge pull request #22 from simeonwillbanks/analytics-and-monitoring

Add Google Analytics and New Relic Monitoring