Update Jekyll up to v2.4.0.

Gemfile

@@ -1,6 +1,6 @@
 source 'https://rubygems.org'
 
-gem 'jekyll', '~> 2.1.0'
+gem 'jekyll', '~> 2.4.0'
 gem 'therubyracer'
 gem 'i18n'
 gem 'jekyll-press'

Gemfile.lock

@@ -2,15 +2,15 @@ GEM
   remote: https://rubygems.org/
   specs:
     blankslate (2.1.2.4)
-    celluloid (0.15.2)
+    celluloid (0.16.0)
-      timers (~> 1.1.0)
+      timers (~> 4.0.0)
-    classifier (1.3.4)
+    classifier-reborn (2.0.1)
-      fast-stemmer (>= 1.0.0)
+      fast-stemmer (~> 1.0)
     coderay (1.1.0)
-    coffee-script (2.2.0)
+    coffee-script (2.3.0)
       coffee-script-source
       execjs
-    coffee-script-source (1.7.0)
+    coffee-script-source (1.8.0)
     colorator (0.1)
     css_press (0.3.2)
       csspool-st (= 3.1.2)
@@ -34,21 +34,22 @@ GEM
       em-websocket (~> 0.5)
       guard (~> 2.0)
       multi_json (~> 1.8)
+    hitimes (1.2.2)
     html_press (0.8.2)
       htmlentities
       multi_css (>= 0.1.0)
       multi_js (>= 0.1.0)
     htmlentities (4.3.2)
     http_parser.rb (0.6.0)
-    i18n (0.6.9)
+    i18n (0.6.11)
-    jekyll (2.1.0)
+    jekyll (2.4.0)
-      classifier (~> 1.3)
+      classifier-reborn (~> 2.0)
       colorator (~> 0.1)
       jekyll-coffeescript (~> 1.0)
       jekyll-gist (~> 1.0)
       jekyll-paginate (~> 1.0)
       jekyll-sass-converter (~> 1.0)
-      jekyll-watch (~> 1.0)
+      jekyll-watch (~> 1.1)
       kramdown (~> 1.3)
       liquid (~> 2.6.1)
       mercenary (~> 0.3.3)
@@ -56,7 +57,7 @@ GEM
       redcarpet (~> 3.1)
       safe_yaml (~> 1.0)
       toml (~> 0.1.0)
-    jekyll-coffeescript (1.0.0)
+    jekyll-coffeescript (1.0.1)
       coffee-script (~> 2.2)
     jekyll-gist (1.1.0)
     jekyll-paginate (1.0.0)
@@ -65,20 +66,20 @@ GEM
       jekyll
       multi_css (>= 0.1.0)
       multi_js (>= 0.1.0)
-    jekyll-sass-converter (1.0.0)
+    jekyll-sass-converter (1.2.1)
       sass (~> 3.2)
-    jekyll-watch (1.0.0)
+    jekyll-watch (1.1.1)
       listen (~> 2.7)
     json (1.8.1)
-    kramdown (1.4.0)
+    kramdown (1.4.1)
-    libv8 (3.16.14.3)
+    libv8 (3.16.14.7)
     liquid (2.6.1)
     listen (2.7.9)
       celluloid (>= 0.15.2)
       rb-fsevent (>= 0.9.3)
       rb-inotify (>= 0.9)
     lumberjack (1.0.9)
-    mercenary (0.3.3)
+    mercenary (0.3.4)
     method_source (0.8.2)
     multi_css (0.1.0)
       css_press
@@ -87,8 +88,8 @@ GEM
     multi_json (1.10.1)
     parslet (1.5.0)
       blankslate (~> 2.0)
-    posix-spawn (0.3.8)
+    posix-spawn (0.3.9)
-    pry (0.10.0)
+    pry (0.10.1)
       coderay (~> 1.1.0)
       method_source (~> 0.8.1)
       slop (~> 3.4)
@@ -101,16 +102,17 @@ GEM
     redcarpet (3.1.2)
     ref (1.0.5)
     safe_yaml (1.0.3)
-    sass (3.3.9)
+    sass (3.4.4)
-    slop (3.5.0)
+    slop (3.6.0)
     therubyracer (0.12.1)
       libv8 (~> 3.16.14.0)
       ref
     thor (0.19.1)
-    timers (1.1.0)
+    timers (4.0.1)
+      hitimes
     toml (0.1.1)
       parslet (~> 1.5.0)
-    uglifier (2.5.1)
+    uglifier (2.5.3)
       execjs (>= 0.3.0)
       json (>= 1.8.0)
     yajl-ruby (1.1.0)
@@ -121,6 +123,6 @@ PLATFORMS
 DEPENDENCIES
   guard-livereload
   i18n
-  jekyll (~> 2.1.0)
+  jekyll (~> 2.4.0)
   jekyll-press
   therubyracer