upgrade rails to 4.2.8 to be compatibale with ruby 2.4.x

Gemfile

@@ -1,7 +1,7 @@
 source 'https://rubygems.org'
 
 # Bundle edge Rails instead: gem 'rails', github: 'rails/rails'
-gem 'rails', '4.2.6'
+gem 'rails', '4.2.8'
 
 gem 'actionpack-page_caching'
 

Gemfile.lock

@@ -1,40 +1,39 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    actionmailer (4.2.6)
-      actionpack (= 4.2.6)
-      actionview (= 4.2.6)
-      activejob (= 4.2.6)
+    actionmailer (4.2.8)
+      actionpack (= 4.2.8)
+      actionview (= 4.2.8)
+      activejob (= 4.2.8)
       mail (~> 2.5, >= 2.5.4)
       rails-dom-testing (~> 1.0, >= 1.0.5)
-    actionpack (4.2.6)
-      actionview (= 4.2.6)
-      activesupport (= 4.2.6)
+    actionpack (4.2.8)
+      actionview (= 4.2.8)
+      activesupport (= 4.2.8)
       rack (~> 1.6)
       rack-test (~> 0.6.2)
       rails-dom-testing (~> 1.0, >= 1.0.5)
       rails-html-sanitizer (~> 1.0, >= 1.0.2)
     actionpack-page_caching (1.1.0)
       actionpack (>= 4.0.0, < 6)
-    actionview (4.2.6)
-      activesupport (= 4.2.6)
+    actionview (4.2.8)
+      activesupport (= 4.2.8)
       builder (~> 3.1)
       erubis (~> 2.7.0)
       rails-dom-testing (~> 1.0, >= 1.0.5)
-      rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    activejob (4.2.6)
-      activesupport (= 4.2.6)
+      rails-html-sanitizer (~> 1.0, >= 1.0.3)
+    activejob (4.2.8)
+      activesupport (= 4.2.8)
       globalid (>= 0.3.0)
-    activemodel (4.2.6)
-      activesupport (= 4.2.6)
+    activemodel (4.2.8)
+      activesupport (= 4.2.8)
       builder (~> 3.1)
-    activerecord (4.2.6)
-      activemodel (= 4.2.6)
-      activesupport (= 4.2.6)
+    activerecord (4.2.8)
+      activemodel (= 4.2.8)
+      activesupport (= 4.2.8)
       arel (~> 6.0)
-    activesupport (4.2.6)
+    activesupport (4.2.8)
       i18n (~> 0.7)
-      json (~> 1.7, >= 1.7.7)
       minitest (~> 5.1)
       thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
@@ -78,16 +77,16 @@ GEM
     rack (1.6.8)
     rack-test (0.6.3)
       rack (>= 1.0)
-    rails (4.2.6)
-      actionmailer (= 4.2.6)
-      actionpack (= 4.2.6)
-      actionview (= 4.2.6)
-      activejob (= 4.2.6)
-      activemodel (= 4.2.6)
-      activerecord (= 4.2.6)
-      activesupport (= 4.2.6)
+    rails (4.2.8)
+      actionmailer (= 4.2.8)
+      actionpack (= 4.2.8)
+      actionview (= 4.2.8)
+      activejob (= 4.2.8)
+      activemodel (= 4.2.8)
+      activerecord (= 4.2.8)
+      activesupport (= 4.2.8)
       bundler (>= 1.3.0, < 2.0)
-      railties (= 4.2.6)
+      railties (= 4.2.8)
       sprockets-rails
     rails-deprecated_sanitizer (1.0.3)
       activesupport (>= 4.2.0.alpha)
@@ -97,9 +96,9 @@ GEM
       rails-deprecated_sanitizer (>= 1.0.1)
     rails-html-sanitizer (1.0.3)
       loofah (~> 2.0)
-    railties (4.2.6)
-      actionpack (= 4.2.6)
-      activesupport (= 4.2.6)
+    railties (4.2.8)
+      actionpack (= 4.2.8)
+      activesupport (= 4.2.8)
       rake (>= 0.8.7)
       thor (>= 0.18.1, < 2.0)
     rake (12.0.0)
@@ -147,7 +146,7 @@ DEPENDENCIES
   jbuilder (~> 1.2)
   jquery-rails
   mysql2
-  rails (= 4.2.6)
+  rails (= 4.2.8)
   sass-rails (~> 4.0.0)
   sdoc
   therubyracer

config/environments/production.rb

@@ -22,7 +22,7 @@
   # config.action_dispatch.rack_cache = true
 
   # Disable Rails's static asset server (Apache or nginx will already do this).
-  config.serve_static_assets = false
+  config.serve_static_files = false
 
   # Compress JavaScripts and CSS.
   config.assets.js_compressor  = :uglifier