Normalize url

This patch implements the net (after conversation) functionality of the following two bullets on the Walker Project Plan

* Ensure we normalize URLs (NOTE: some of these may be a non-issue, just want to check them):
* Configurable parameter exclusion (case insensitive) with defaults: jsessionid, phpsessid, aspsessionid

First PP, yea missed the Encode method on values, that'll slim the code down.

Not sure I understand the second paragraph. Are you implying that we want to purge the session-ids regardless of case? I.e. jsessionid, JSESSIONID, and JsessIONid should all be removed?