Replace negative lookbehind with a more supported regular expression (#837)

* provide fix for bug related to parsing GET parameters

* expand to test for a path that has already escaped the query string

* remove negative lookbehind and replaced with alternative regexp due to firefox incompatibility

* follow code style

Author: kyle-mccarthy

js/core.js

@@ -235,7 +235,7 @@ proto.updateGetPathTemplate = function( optPath ) {
   // convert path option into regex to look for pattern in location
   // escape query (?) in url, allows for parsing GET parameters 
   var regexString = optPath
-    .replace( /(?<!\\)\?/, '\\?' )
+    .replace( /(\\\?|\?)/, '\\?' )
     .replace( '{{#}}', '(\\d\\d?\\d?)' );
   var templateRe = new RegExp( regexString );
   var match = location.href.match( templateRe );