Merge branch 'upgrade-sprockets-rails' into 'master'

Upgrade sprockets and sprockets rails, remove quiet_assets

## What does this MR do?

Upgrade Sprockets from 3.6.0 to 3.6.2.

Changelog: https://github.com/rails/sprockets/blob/3.x/CHANGELOG.md

Upgrade Sprockets Rails from 3.0.4 to 3.1.1.

Changelog: https://github.com/rails/sprockets-rails/compare/v3.0.4...v3.1.1

quiet_assets has been seemingly abandoned, and now sprockets-rails has the feature built-in!

The config was added in this PR: https://github.com/rails/sprockets-rails/pull/355

Working towards #14286.

See merge request !5029

Gemfile

@@ -251,7 +251,6 @@ group :development do
   gem 'brakeman', '~> 3.3.0', require: false
 
   gem 'letter_opener_web', '~> 1.3.0'
-  gem 'quiet_assets', '~> 1.0.2'
   gem 'rerun', '~> 0.11.0'
   gem 'bullet', require: false
   gem 'rblineprof', platform: :mri, require: false

Gemfile.lock

@@ -499,8 +499,6 @@ GEM
     pry-rails (0.3.4)
       pry (>= 0.9.10)
     pyu-ruby-sasl (0.0.3.3)
-    quiet_assets (1.0.3)
-      railties (>= 3.1, < 5.0)
     rack (1.6.4)
     rack-accept (0.4.5)
       rack (>= 0.4)
@@ -700,10 +698,10 @@ GEM
       spring (>= 0.9.1)
     spring-commands-teaspoon (0.0.2)
       spring (>= 0.9.1)
-    sprockets (3.6.0)
+    sprockets (3.6.2)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
-    sprockets-rails (3.0.4)
+    sprockets-rails (3.1.1)
       actionpack (>= 4.0)
       activesupport (>= 4.0)
       sprockets (>= 3.0.0)
@@ -920,7 +918,6 @@ DEPENDENCIES
   poltergeist (~> 1.9.0)
   premailer-rails (~> 1.9.0)
   pry-rails
-  quiet_assets (~> 1.0.2)
   rack-attack (~> 4.3.1)
   rack-cors (~> 0.4.0)
   rack-oauth2 (~> 1.2.1)

config/environments/development.rb

@@ -42,4 +42,7 @@ Rails.application.configure do
   config.action_mailer.preview_path = 'spec/mailers/previews'
 
   config.eager_load = false
+
+  # Do not log asset requests
+  config.assets.quiet = true
 end