[browser] Avoid double slashes when initing the router's current route

[This change](https://github.com/flatiron/director/commit/e2ad856be0f05fcaa2509537a1d6ed9c54374ca3#diff-20711cb07e3243d3358513b78a0778a7R213) in e2ad856be0f05fcaa2509537a1d6ed9c54374ca3 results in hash fragments already starting with `/` (e.g `#/login`) to be evaluated to `//login`, thus matching no route at all.

This replaces `#`, `#/` and `/` in the beginning of the path and prepends `/` in order to fix this.