Update Rails to v5.1.2 (#3968)

Gemfile.lock

@@ -1,40 +1,40 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    actioncable (5.1.1)
-      actionpack (= 5.1.1)
+    actioncable (5.1.2)
+      actionpack (= 5.1.2)
       nio4r (~> 2.0)
       websocket-driver (~> 0.6.1)
-    actionmailer (5.1.1)
-      actionpack (= 5.1.1)
-      actionview (= 5.1.1)
-      activejob (= 5.1.1)
+    actionmailer (5.1.2)
+      actionpack (= 5.1.2)
+      actionview (= 5.1.2)
+      activejob (= 5.1.2)
       mail (~> 2.5, >= 2.5.4)
       rails-dom-testing (~> 2.0)
-    actionpack (5.1.1)
-      actionview (= 5.1.1)
-      activesupport (= 5.1.1)
+    actionpack (5.1.2)
+      actionview (= 5.1.2)
+      activesupport (= 5.1.2)
       rack (~> 2.0)
       rack-test (~> 0.6.3)
       rails-dom-testing (~> 2.0)
       rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    actionview (5.1.1)
-      activesupport (= 5.1.1)
+    actionview (5.1.2)
+      activesupport (= 5.1.2)
       builder (~> 3.1)
       erubi (~> 1.4)
       rails-dom-testing (~> 2.0)
       rails-html-sanitizer (~> 1.0, >= 1.0.3)
     active_record_query_trace (1.5.4)
-    activejob (5.1.1)
-      activesupport (= 5.1.1)
+    activejob (5.1.2)
+      activesupport (= 5.1.2)
       globalid (>= 0.3.6)
-    activemodel (5.1.1)
-      activesupport (= 5.1.1)
-    activerecord (5.1.1)
-      activemodel (= 5.1.1)
-      activesupport (= 5.1.1)
+    activemodel (5.1.2)
+      activesupport (= 5.1.2)
+    activerecord (5.1.2)
+      activemodel (= 5.1.2)
+      activesupport (= 5.1.2)
       arel (~> 8.0)
-    activesupport (5.1.1)
+    activesupport (5.1.2)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (~> 0.7)
       minitest (~> 5.1)
@@ -298,17 +298,17 @@ GEM
     rack-test (0.6.3)
       rack (>= 1.0)
     rack-timeout (0.4.2)
-    rails (5.1.1)
-      actioncable (= 5.1.1)
-      actionmailer (= 5.1.1)
-      actionpack (= 5.1.1)
-      actionview (= 5.1.1)
-      activejob (= 5.1.1)
-      activemodel (= 5.1.1)
-      activerecord (= 5.1.1)
-      activesupport (= 5.1.1)
+    rails (5.1.2)
+      actioncable (= 5.1.2)
+      actionmailer (= 5.1.2)
+      actionpack (= 5.1.2)
+      actionview (= 5.1.2)
+      activejob (= 5.1.2)
+      activemodel (= 5.1.2)
+      activerecord (= 5.1.2)
+      activesupport (= 5.1.2)
       bundler (>= 1.3.0, < 2.0)
-      railties (= 5.1.1)
+      railties (= 5.1.2)
       sprockets-rails (>= 2.0.0)
     rails-controller-testing (1.0.2)
       actionpack (~> 5.x, >= 5.0.1)
@@ -324,9 +324,9 @@ GEM
       railties (~> 5.0)
     rails-settings-cached (0.6.5)
       rails (>= 4.2.0)
-    railties (5.1.1)
-      actionpack (= 5.1.1)
-      activesupport (= 5.1.1)
+    railties (5.1.2)
+      actionpack (= 5.1.2)
+      activesupport (= 5.1.2)
       method_source
       rake (>= 0.8.7)
       thor (>= 0.18.1, < 2.0)