Explicitly require the CGI gem

This prevents uninitialized constant errors for environments where there isn't another gem already requiring CGI

Author: itsliamegan

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