Update devDependencies and gems.

Also lock babel versions, since we get failures with newer ones.

Gemfile.lock

@@ -16,7 +16,7 @@ GEM
     http_parser.rb (0.6.0)
     i18n (0.9.5)
       concurrent-ruby (~> 1.0)
-    jekyll (3.8.5)
+    jekyll (3.8.6)
       addressable (~> 2.4)
       colorator (~> 1.0)
       em-websocket (~> 0.5)
@@ -53,11 +53,11 @@ GEM
       mini_portile2 (~> 2.4.0)
     pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (3.1.0)
+    public_suffix (3.1.1)
     rb-fsevent (0.10.3)
     rb-inotify (0.10.0)
       ffi (~> 1.0)
-    rouge (3.4.1)
+    rouge (3.6.0)
     ruby_dep (1.5.0)
     safe_yaml (1.0.5)
     sass (3.7.4)
@@ -72,7 +72,7 @@ PLATFORMS
   x64-mingw32
 
 DEPENDENCIES
-  jekyll (~> 3.8.5)
+  jekyll (~> 3.8.6)
   jekyll-redirect-from (~> 0.15.0)
   jekyll-sitemap (~> 1.3.1)
   jekyll-toc (~> 0.11.0)