HTML: Add a missing require

Author: orgads

lib/ruby-handlebars/escapers/html_escaper.rb

@@ -1,3 +1,5 @@
+require 'cgi'
+
 module Handlebars
   module Escapers
     class HTMLEscaper
@@ -6,4 +8,4 @@ def self.escape(value)
       end
     end
   end
-end
+end