update gems to latest versions

Gemfile.lock

@@ -1,11 +1,10 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (4.2.6)
+    activesupport (5.1.4)
+      concurrent-ruby (~> 1.0, >= 1.0.2)
       i18n (~> 0.7)
-      json (~> 1.7, >= 1.7.7)
       minitest (~> 5.1)
-      thread_safe (~> 0.3, >= 0.3.4)
       tzinfo (~> 1.1)
     addressable (2.4.0)
     bourbon (4.0.2)
@@ -14,14 +13,15 @@ GEM
     coffee-script (2.4.1)
       coffee-script-source
       execjs
-    coffee-script-source (1.10.0)
+    coffee-script-source (1.12.2)
     colorator (0.1)
-    ethon (0.9.0)
+    concurrent-ruby (1.0.5)
+    ethon (0.11.0)
       ffi (>= 1.3.0)
     execjs (2.7.0)
-    faraday (0.9.2)
+    faraday (0.14.0)
       multipart-post (>= 1.2, < 3)
-    ffi (1.9.10)
+    ffi (1.9.21)
     gemoji (2.1.0)
     github-pages (82)
       github-pages-health-check (= 1.1.0)
@@ -49,10 +49,11 @@ GEM
       octokit (~> 4.0)
       public_suffix (~> 1.4)
       typhoeus (~> 0.7)
-    html-pipeline (2.4.1)
-      activesupport (>= 2, < 5)
+    html-pipeline (2.7.1)
+      activesupport (>= 2)
       nokogiri (>= 1.4)
-    i18n (0.7.0)
+    i18n (0.9.4)
+      concurrent-ruby (~> 1.0)
     jekyll (3.1.6)
       colorator (~> 0.1)
       jekyll-sass-converter (~> 1.0)
@@ -81,49 +82,48 @@ GEM
     jekyll-seo-tag (2.0.0)
       jekyll (~> 3.1)
     jekyll-sitemap (0.10.0)
-    jekyll-watch (1.4.0)
-      listen (~> 3.0, < 3.1)
+    jekyll-watch (1.5.1)
+      listen (~> 3.0)
     jemoji (0.6.2)
       gemoji (~> 2.0)
       html-pipeline (~> 2.2)
       jekyll (>= 3.0)
-    json (1.8.3)
     kramdown (1.10.0)
     liquid (3.0.6)
     listen (3.0.6)
       rb-fsevent (>= 0.9.3)
       rb-inotify (>= 0.9.7)
     mercenary (0.3.6)
-    mini_portile2 (2.1.0)
-    minitest (5.9.0)
+    mini_portile2 (2.3.0)
+    minitest (5.11.3)
     multipart-post (2.0.0)
     neat (1.6.0)
       bourbon (>= 3.1)
       sass (>= 3.3)
     net-dns (0.8.0)
-    nokogiri (1.6.8)
-      mini_portile2 (~> 2.1.0)
-      pkg-config (~> 1.1.7)
-    octokit (4.3.0)
-      sawyer (~> 0.7.0, >= 0.5.3)
-    pkg-config (1.1.7)
+    nokogiri (1.8.2)
+      mini_portile2 (~> 2.3.0)
+    octokit (4.8.0)
+      sawyer (~> 0.8.0, >= 0.5.3)
     public_suffix (1.5.3)
-    rb-fsevent (0.9.7)
-    rb-inotify (0.9.7)
-      ffi (>= 0.5.0)
+    rb-fsevent (0.10.2)
+    rb-inotify (0.9.10)
+      ffi (>= 0.5.0, < 2)
     rouge (1.10.1)
     safe_yaml (1.0.4)
-    sass (3.4.22)
-    sawyer (0.7.0)
-      addressable (>= 2.3.5, < 2.5)
-      faraday (~> 0.8, < 0.10)
-    terminal-table (1.6.0)
-    thor (0.19.1)
-    thread_safe (0.3.5)
+    sass (3.4.25)
+    sawyer (0.8.1)
+      addressable (>= 2.3.5, < 2.6)
+      faraday (~> 0.8, < 1.0)
+    terminal-table (1.8.0)
+      unicode-display_width (~> 1.1, >= 1.1.1)
+    thor (0.20.0)
+    thread_safe (0.3.6)
     typhoeus (0.8.0)
       ethon (>= 0.8.0)
-    tzinfo (1.2.2)
+    tzinfo (1.2.5)
       thread_safe (~> 0.1)
+    unicode-display_width (1.3.0)
 
 PLATFORMS
   ruby
@@ -135,4 +135,4 @@ DEPENDENCIES
   sass (~> 3.4.22)
 
 BUNDLED WITH
-   1.12.4
+   1.16.1