Upgrade Middleman to v4

Gemfile

@@ -1,12 +1,10 @@
 source 'https://rubygems.org'
 
 gem 'rake'
-gem 'middleman', '~> 3.3.12'
-gem 'middleman-livereload', '~> 3.4.3'
+gem 'middleman', '~> 4.1.10'
+gem 'middleman-livereload', '~> 3.4.6'
 
 gem 'therubyracer', require: false
-gem 'bootstrap-sass', '~> 3', require: false
-gem 'font-awesome-sass', '~> 4', require: false
 
 gem 'wdm', '~> 0.1.1', platforms: %i(mswin mingw), require: false
-gem 'tzinfo-data', platforms: %i(mswin mingw jruby), require: false
+gem 'tzinfo-data', '~> 1.2016.6', platforms: %i(mswin mingw jruby), require: false

source/stylesheets/all.scss → source/stylesheets/all.css.scss

@@ -9,7 +9,7 @@
 }
 
 html {
-	font-family: Arial, Helvetica, sans-serif;
+	font-family: Tahoma, "Helvetica Neue", Helvetica, Arial, sans-serif;
 }
 
 body {