Removed the ticket GET param from the service, as it could break CAS.

When interacting with a CAS 2 server (tested against a fairly stock http://jasig.github.io/cas/4.0.0/index.html), this client appends the ticket to the service URL, which modifies the service URL, causing an invalid request to propagate and ultimately fail.

Regex has been added to remove the ticket get parameter from the string generated by request.get_full_path.