Bump rails from 5.1.4 to 5.1.5

Bumps [rails](https://github.com/rails/rails) from 5.1.4 to 5.1.5.
- [Commits](rails/rails@v5.1.4...v5.1.5)

Gemfile

@@ -9,7 +9,7 @@ gem 'govuk_frontend_toolkit', '~> 7.4.1'
 gem 'govuk_navigation_helpers', '9.0.0'
 gem 'govuk_publishing_components', '~> 5.2.2'
 gem 'plek', '~> 2.1.1'
-gem 'rails', '5.1.4'
+gem 'rails', '5.1.5'
 gem 'sass-rails', '~> 5.0.3'
 gem 'slimmer', '~> 12.0.0'
 gem 'uglifier', '~> 4.1.6'

Gemfile.lock

@@ -2,39 +2,39 @@ GEM
   remote: https://rubygems.org/
   specs:
     PriorityQueue (0.1.2)
-    actioncable (5.1.4)
-      actionpack (= 5.1.4)
+    actioncable (5.1.5)
+      actionpack (= 5.1.5)
       nio4r (~> 2.0)
       websocket-driver (~> 0.6.1)
-    actionmailer (5.1.4)
-      actionpack (= 5.1.4)
-      actionview (= 5.1.4)
-      activejob (= 5.1.4)
+    actionmailer (5.1.5)
+      actionpack (= 5.1.5)
+      actionview (= 5.1.5)
+      activejob (= 5.1.5)
       mail (~> 2.5, >= 2.5.4)
       rails-dom-testing (~> 2.0)
-    actionpack (5.1.4)
-      actionview (= 5.1.4)
-      activesupport (= 5.1.4)
+    actionpack (5.1.5)
+      actionview (= 5.1.5)
+      activesupport (= 5.1.5)
       rack (~> 2.0)
       rack-test (>= 0.6.3)
       rails-dom-testing (~> 2.0)
       rails-html-sanitizer (~> 1.0, >= 1.0.2)
-    actionview (5.1.4)
-      activesupport (= 5.1.4)
+    actionview (5.1.5)
+      activesupport (= 5.1.5)
       builder (~> 3.1)
       erubi (~> 1.4)
       rails-dom-testing (~> 2.0)
       rails-html-sanitizer (~> 1.0, >= 1.0.3)
-    activejob (5.1.4)
-      activesupport (= 5.1.4)
+    activejob (5.1.5)
+      activesupport (= 5.1.5)
       globalid (>= 0.3.6)
-    activemodel (5.1.4)
-      activesupport (= 5.1.4)
-    activerecord (5.1.4)
-      activemodel (= 5.1.4)
-      activesupport (= 5.1.4)
+    activemodel (5.1.5)
+      activesupport (= 5.1.5)
+    activerecord (5.1.5)
+      activemodel (= 5.1.5)
+      activesupport (= 5.1.5)
       arel (~> 8.0)
-    activesupport (5.1.4)
+    activesupport (5.1.5)
       concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (~> 0.7)
       minitest (~> 5.1)
@@ -94,7 +94,7 @@ GEM
     docile (1.1.5)
     domain_name (0.5.20170404)
       unf (>= 0.0.5, < 1.0.0)
-    erubi (1.7.0)
+    erubi (1.7.1)
     execjs (2.7.0)
     faraday (0.14.0)
       multipart-post (>= 1.2, < 3)
@@ -223,28 +223,28 @@ GEM
     rack (2.0.4)
     rack-cache (1.7.1)
       rack (>= 0.4)
-    rack-test (0.8.2)
+    rack-test (0.8.3)
       rack (>= 1.0, < 3)
-    rails (5.1.4)
-      actioncable (= 5.1.4)
-      actionmailer (= 5.1.4)
-      actionpack (= 5.1.4)
-      actionview (= 5.1.4)
-      activejob (= 5.1.4)
-      activemodel (= 5.1.4)
-      activerecord (= 5.1.4)
-      activesupport (= 5.1.4)
+    rails (5.1.5)
+      actioncable (= 5.1.5)
+      actionmailer (= 5.1.5)
+      actionpack (= 5.1.5)
+      actionview (= 5.1.5)
+      activejob (= 5.1.5)
+      activemodel (= 5.1.5)
+      activerecord (= 5.1.5)
+      activesupport (= 5.1.5)
       bundler (>= 1.3.0)
-      railties (= 5.1.4)
+      railties (= 5.1.5)
       sprockets-rails (>= 2.0.0)
     rails-dom-testing (2.0.3)
       activesupport (>= 4.2.0)
       nokogiri (>= 1.6)
     rails-html-sanitizer (1.0.3)
       loofah (~> 2.0)
-    railties (5.1.4)
-      actionpack (= 5.1.4)
-      activesupport (= 5.1.4)
+    railties (5.1.5)
+      actionpack (= 5.1.5)
+      activesupport (= 5.1.5)
       method_source
       rake (>= 0.8.7)
       thor (>= 0.18.1, < 2.0)
@@ -361,7 +361,7 @@ DEPENDENCIES
   plek (~> 2.1.1)
   poltergeist
   pry-byebug
-  rails (= 5.1.4)
+  rails (= 5.1.5)
   sass-rails (~> 5.0.3)
   simplecov
   simplecov-rcov