Add the scout gem to production

Gemfile

@@ -109,6 +109,8 @@ group :production, :staging do
   gem 'memcachier'
   gem 'newrelic_rpm'
   gem 'rails_12factor' # supresses heroku plugin injection
+
+  gem 'scout_apm' # monitoring
 end
 
 group :development do

Gemfile.lock

@@ -453,6 +453,7 @@ GEM
       sprockets (> 3.0)
       sprockets-rails
       tilt
+    scout_apm (2.4.24)
     selenium-webdriver (3.141.0)
       childprocess (~> 0.5)
       rubyzip (~> 1.2, >= 1.2.2)
@@ -588,6 +589,7 @@ DEPENDENCIES
   rubocop-rspec
   ruby-units
   sass-rails
+  scout_apm
   selenium-webdriver
   sidekiq
   timecop