Replace apostrophe with empty string (like github)

Github treats apostrophe as empty string. Hence, slugger should do the same.

Author: parthpp

index.js

@@ -4,7 +4,7 @@ module.exports = BananaSlug
 
 var own = Object.hasOwnProperty
 var whitespace = /\s/g
-var specials = /[\u2000-\u206F\u2E00-\u2E7F\\'!"#$%&()*+,./:;<=>?@[\]^`{|}~]/g
+var specials = /[\u2000-\u206F\u2E00-\u2E7F\\'!"#$%&()*+,./:;<=>?@[\]^`{|}~’]/g
 
 function BananaSlug () {
   var self = this