Rescue the redirection to give the path a second chance

* redirect was not working on paths with extensions
* Cmsimple::Path#from_request was raising RecordNotFound and
not looking to the request for the fullpath

@gvarela I wasn't sure how you felt about this solution. on one hand, it seems a little clunky for the model not to handle the RecordNotFound, on the other, I think its a little more robust to look to the request object itself to find the :fullpath in order to make the uri comparison since when a Redirection is created it seems that people type the entire relative url, like `/MyPage.aspx`. anyway, this seems to work, but I'm happy to revisit if you have concerns.