Add custom routeStripper and rootStripper option for Chaplin.Route.

## Why
I need to support hashbang `#!` in Backbone.History, which means I need to make url like `#!user/:user_id/projects` transparently redirect to `user/:user_id/projects` but the default options doesn't include hook for me to pass my custom regex, so I made this pr, please consider it, thanks!