Strip MailChimp campaign tracking tokens

Strip `mc_cid` and `mc_eid` query string parameters.

Closes #12

Author: jparise

background.js

@@ -3,15 +3,15 @@
  * parameter. We'll search the query string portion of the URL for this
  * pattern to determine if there's any stripping work to do.
  */
-var searchPattern = new RegExp('utm_|clid|icid|mkt_tok', 'i');
+var searchPattern = new RegExp('utm_|clid|icid|mc_|mkt_tok', 'i');
 
 /*
  * Pattern matching the query string parameters (key=value) that will be
  * stripped from the final URL.
  */
 var replacePattern = new RegExp(
     '([?&]' +
-    '(icid|mkt_tok|(g|fb)clid|utm_(source|medium|term|campaign|content|cid|reader|referrer|name))' +
+    '(icid|mkt_tok|(g|fb)clid|mc_[ce]id|utm_(source|medium|term|campaign|content|cid|reader|referrer|name))' +
     '=[^&#]*)',
     'ig');