replace silence_assets.rb with quiet_assets gem

Gemfile

@@ -280,4 +280,7 @@ group :development, :test do
   gem "jasmine-jquery-rails",      "2.0.3"
   gem "rails-assets-jasmine-ajax", "3.1.1", source: "https://rails-assets.org"
   gem "sinon-rails",               "1.10.3"
+
+  # silence assets
+  gem "quiet_assets", "1.1.0"
 end

Gemfile.lock

@@ -468,6 +468,8 @@ GEM
       pry (~> 0.10)
     pry-debundle (0.8)
       pry
+    quiet_assets (1.1.0)
+      railties (>= 3.1, < 5.0)
     rack (1.6.1)
     rack-cors (0.4.0)
     rack-google-analytics (1.2.0)
@@ -781,6 +783,7 @@ DEPENDENCIES
   pry
   pry-byebug
   pry-debundle
+  quiet_assets (= 1.1.0)
   rack-cors (= 0.4.0)
   rack-google-analytics (= 1.2.0)
   rack-piwik (= 0.3.0)

config/initializers/silence_assets.rb

-if Rails.env.development?
-
-  Rails.application.assets.logger = Logger.new('/dev/null')
-
-  Rails::Rack::Logger.class_eval do
-    def call_with_quiet_assets(env)
-      previous_level = Rails.logger.level
-      Rails.logger.level = Logger::ERROR if env['PATH_INFO'] =~ %r{^/assets/}
-      call_without_quiet_assets(env)
-    ensure
-      Rails.logger.level = previous_level
-    end
-    alias_method_chain :call, :quiet_assets
-  end
-
-end
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