Update Jekyll to address security vulnerability (pulumi#637)

Also update npm packages.

Author: justinvp

Gemfile

@@ -1,6 +1,6 @@
 source "https://rubygems.org"
 
-gem "jekyll", "3.6.2"
+gem "jekyll"
 # https://github.com/primer/jekyll-octicons
 gem "jekyll-octicons"
 gem "kramdown"

Gemfile.lock

@@ -4,18 +4,28 @@ GEM
     addressable (2.5.2)
       public_suffix (>= 2.0.2, < 4.0)
     colorator (1.1.0)
-    ffi (1.9.23)
+    concurrent-ruby (1.0.5)
+    em-websocket (0.5.1)
+      eventmachine (>= 0.12.9)
+      http_parser.rb (~> 0.6.0)
+    eventmachine (1.2.7)
+    ffi (1.9.25)
     forwardable-extended (2.6.0)
-    jekyll (3.6.2)
+    http_parser.rb (0.6.0)
+    i18n (0.9.5)
+      concurrent-ruby (~> 1.0)
+    jekyll (3.8.4)
       addressable (~> 2.4)
       colorator (~> 1.0)
+      em-websocket (~> 0.5)
+      i18n (~> 0.7)
       jekyll-sass-converter (~> 1.0)
-      jekyll-watch (~> 1.1)
+      jekyll-watch (~> 2.0)
       kramdown (~> 1.14)
       liquid (~> 4.0)
       mercenary (~> 0.3.3)
       pathutil (~> 0.9)
-      rouge (>= 1.7, < 3)
+      rouge (>= 1.7, < 4)
       safe_yaml (~> 1.0)
     jekyll-include-cache (0.1.0)
       jekyll (~> 3.3)
@@ -32,10 +42,10 @@ GEM
       sass (~> 3.4)
     jekyll-sitemap (1.2.0)
       jekyll (~> 3.3)
-    jekyll-watch (1.5.1)
+    jekyll-watch (2.1.2)
       listen (~> 3.0)
-    kramdown (1.16.2)
-    liquid (4.0.0)
+    kramdown (1.17.0)
+    liquid (4.0.1)
     listen (3.1.5)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
@@ -46,16 +56,16 @@ GEM
       mini_portile2 (~> 2.3.0)
     octicons (5.3.0)
       nokogiri (>= 1.6.3.1)
-    pathutil (0.16.1)
+    pathutil (0.16.2)
       forwardable-extended (~> 2.6)
-    public_suffix (3.0.2)
+    public_suffix (3.0.3)
     rb-fsevent (0.10.3)
     rb-inotify (0.9.10)
       ffi (>= 0.5.0, < 2)
-    rouge (2.2.1)
+    rouge (3.3.0)
     ruby_dep (1.5.0)
     safe_yaml (1.0.4)
-    sass (3.5.6)
+    sass (3.6.0)
       sass-listen (~> 4.0.0)
     sass-listen (4.0.0)
       rb-fsevent (~> 0.9, >= 0.9.4)
@@ -65,7 +75,7 @@ PLATFORMS
   ruby
 
 DEPENDENCIES
-  jekyll (= 3.6.2)
+  jekyll
   jekyll-include-cache (~> 0.1)
   jekyll-octicons
   jekyll-optional-front-matter