support routes for url rewriting

This commit adds support for routes in the injected filepaths. Can be useful if a templating engine (Jade, HAML, etc.) is *wired* before compilation and output in another folder.

```
bower_components/   <- libraries
views/              <- Jade files
public/             <- HTTP server root, serves HTML files and assets
  lib/              <- main Bower files
```

Without routes, the HTML files point to `../bower_components/<path>`, when I need them to point to `/lib/<path>`.

We can work this out with a custom replace function, but I think routes add some flexibility to this.