replacing instances of // with / before path checking

The path verification logic with certificates prior to v3 would treat the urls  /foo/bar/  and /foo//bar/ as the same.  i.e. It would treat double forward slashes as one.  The v3 logic does not do this and will not validate that /foo//bar/ matches /foo/bar/.

To validate this, simply run the tests with my two added assertions.  The v3 one will fail, the v2 one will pass.  

This commit does a manual replace of // with / in the path before any validation.  I can see an argument for putting this within the path_tree code since the pre-v3 cert code already handles this fine, but I think it also makes sense (and is simpler) to do this prior to passing to either equality checks.