Bundle update; upgrade middleman, add sass gem

Patch taken from #1092, thanks jakemack

Gemfile

@@ -2,10 +2,11 @@ ruby '>=2.3.1'
 source 'https://rubygems.org'
 
 # Middleman
-gem 'middleman', '~>4.2.1'
-gem 'middleman-syntax', '~> 3.0.0'
-gem 'middleman-autoprefixer', '~> 2.7.0'
-gem 'middleman-sprockets', '~> 4.1.0'
+gem 'middleman', '~>4.3'
+gem 'middleman-syntax', '~> 3.0'
+gem 'middleman-autoprefixer', '~> 2.7'
+gem 'middleman-sprockets', '~> 4.1'
 gem 'rouge', '~> 2.0.5'
 gem 'redcarpet', '~> 3.4.0'
 gem 'nokogiri', '~> 1.8.5'
+gem 'sass'

Gemfile.lock

@@ -1,60 +1,57 @@
 GEM
   remote: https://rubygems.org/
   specs:
-    activesupport (5.0.1)
+    activesupport (5.0.7.2)
       concurrent-ruby (~> 1.0, >= 1.0.2)
-      i18n (~> 0.7)
+      i18n (>= 0.7, < 2)
       minitest (~> 5.1)
       tzinfo (~> 1.1)
-    addressable (2.5.0)
-      public_suffix (~> 2.0, >= 2.0.2)
-    autoprefixer-rails (6.6.1)
+    addressable (2.6.0)
+      public_suffix (>= 2.0.2, < 4.0)
+    autoprefixer-rails (9.5.1.1)
       execjs
-    backports (3.6.8)
+    backports (3.15.0)
     coffee-script (2.4.1)
       coffee-script-source
       execjs
     coffee-script-source (1.12.2)
-    compass-import-once (1.0.5)
-      sass (>= 3.2, < 3.5)
-    concurrent-ruby (1.0.5)
+    concurrent-ruby (1.1.5)
     contracts (0.13.0)
-    dotenv (2.2.0)
+    dotenv (2.7.2)
     erubis (2.7.0)
     execjs (2.7.0)
     fast_blank (1.0.0)
-    fastimage (2.0.1)
-      addressable (~> 2)
-    ffi (1.9.25)
-    haml (4.0.7)
+    fastimage (2.1.5)
+    ffi (1.11.1)
+    haml (5.1.1)
+      temple (>= 0.8.0)
       tilt
     hamster (3.0.0)
       concurrent-ruby (~> 1.0)
-    hashie (3.5.1)
-    i18n (0.7.0)
-    kramdown (1.13.2)
+    hashie (3.6.0)
+    i18n (0.9.5)
+      concurrent-ruby (~> 1.0)
+    kramdown (1.17.0)
     listen (3.0.8)
       rb-fsevent (~> 0.9, >= 0.9.4)
       rb-inotify (~> 0.9, >= 0.9.7)
-    memoist (0.15.0)
-    middleman (4.2.1)
+    memoist (0.16.0)
+    middleman (4.3.4)
       coffee-script (~> 2.2)
-      compass-import-once (= 1.0.5)
       haml (>= 4.0.5)
       kramdown (~> 1.2)
-      middleman-cli (= 4.2.1)
-      middleman-core (= 4.2.1)
-      sass (>= 3.4.0, < 4.0)
-    middleman-autoprefixer (2.7.1)
-      autoprefixer-rails (>= 6.5.2, < 7.0.0)
+      middleman-cli (= 4.3.4)
+      middleman-core (= 4.3.4)
+    middleman-autoprefixer (2.10.1)
+      autoprefixer-rails (~> 9.1)
       middleman-core (>= 3.3.3)
-    middleman-cli (4.2.1)
+    middleman-cli (4.3.4)
       thor (>= 0.17.0, < 2.0)
-    middleman-core (4.2.1)
+    middleman-core (4.3.4)
       activesupport (>= 4.2, < 5.1)
       addressable (~> 2.3)
       backports (~> 3.6)
-      bundler (~> 1.1)
+      bundler
       contracts (~> 0.13.0)
       dotenv
       erubis
@@ -63,67 +60,77 @@ GEM
       fastimage (~> 2.0)
       hamster (~> 3.0)
       hashie (~> 3.4)
-      i18n (~> 0.7.0)
+      i18n (~> 0.9.0)
       listen (~> 3.0.0)
       memoist (~> 0.14)
       padrino-helpers (~> 0.13.0)
       parallel
       rack (>= 1.4.5, < 3)
-      sass (>= 3.4)
+      sassc (~> 2.0)
       servolux
-      tilt (~> 2.0)
+      tilt (~> 2.0.9)
       uglifier (~> 3.0)
-    middleman-sprockets (4.1.0)
+    middleman-sprockets (4.1.1)
       middleman-core (~> 4.0)
       sprockets (>= 3.0)
     middleman-syntax (3.0.0)
       middleman-core (>= 3.2)
       rouge (~> 2.0)
     mini_portile2 (2.3.0)
-    minitest (5.10.1)
+    minitest (5.11.3)
     nokogiri (1.8.5)
       mini_portile2 (~> 2.3.0)
-    padrino-helpers (0.13.3.3)
+    padrino-helpers (0.13.3.4)
       i18n (~> 0.6, >= 0.6.7)
-      padrino-support (= 0.13.3.3)
+      padrino-support (= 0.13.3.4)
       tilt (>= 1.4.1, < 3)
-    padrino-support (0.13.3.3)
+    padrino-support (0.13.3.4)
       activesupport (>= 3.1)
-    parallel (1.10.0)
-    public_suffix (2.0.5)
-    rack (2.0.6)
-    rb-fsevent (0.9.8)
-    rb-inotify (0.9.8)
-      ffi (>= 0.5.0)
+    parallel (1.17.0)
+    public_suffix (3.1.0)
+    rack (2.0.7)
+    rake (12.3.2)
+    rb-fsevent (0.10.3)
+    rb-inotify (0.10.0)
+      ffi (~> 1.0)
     redcarpet (3.4.0)
     rouge (2.0.7)
-    sass (3.4.23)
-    servolux (0.12.0)
+    sass (3.7.4)
+      sass-listen (~> 4.0.0)
+    sass-listen (4.0.0)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+    sassc (2.0.1)
+      ffi (~> 1.9)
+      rake
+    servolux (0.13.0)
     sprockets (3.7.2)
       concurrent-ruby (~> 1.0)
       rack (> 1, < 3)
-    thor (0.19.4)
-    thread_safe (0.3.5)
-    tilt (2.0.6)
-    tzinfo (1.2.2)
+    temple (0.8.1)
+    thor (0.20.3)
+    thread_safe (0.3.6)
+    tilt (2.0.9)
+    tzinfo (1.2.5)
       thread_safe (~> 0.1)
-    uglifier (3.0.4)
+    uglifier (3.2.0)
       execjs (>= 0.3.0, < 3)
 
 PLATFORMS
   ruby
 
 DEPENDENCIES
-  middleman (~> 4.2.1)
-  middleman-autoprefixer (~> 2.7.0)
-  middleman-sprockets (~> 4.1.0)
-  middleman-syntax (~> 3.0.0)
+  middleman (~> 4.3)
+  middleman-autoprefixer (~> 2.7)
+  middleman-sprockets (~> 4.1)
+  middleman-syntax (~> 3.0)
   nokogiri (~> 1.8.5)
   redcarpet (~> 3.4.0)
   rouge (~> 2.0.5)
+  sass
 
 RUBY VERSION
    ruby 2.3.3p222
 
 BUNDLED WITH
-   1.15.4
+   2.0.1