Use static_path and route_path

This commit replaces `static_url` by `static_path` and `route_url` by `route_path` in the `ngeo.html` template. `static_url` and `static_url` may not work when behind a proxy. This is related to the Apache `ProxyPreserveHost` directive. See <https://groups.google.com/d/msg/pylons-devel/34BrepVKPsU/_xVzaJDWyfsJ> for a discussion on the Pylons mailing list about that issue.