'path' URL variables that include \'s

I have a case where I need to match against an unknown number of sub-paths after some initial path variables.

I'd like something equivalent to flask's `path` converter (http://flask.pocoo.org/docs/0.12/quickstart/#variable-rules) that will let me match against the remaining path, including any extra /'s.

E.g.

`@app.route('/{prefix}/{path:rest}')`

should match paths like /a/b (prefix=a, rest=b), /a/b/c (prefix=a, rest=b/c), /a/b/c/d.txt (prefix=a, rest=b/c/d.txt), etc.

Start from the app.route declaration described in the issue and compare its requested behavior with Flask's path converter documentation. Trace the route-matching entry point and existing routing tests, then verify that the examples match while preserving slashes in the remaining path.

Written by the indexing model from the issue text.