routerLink can't set href to components defined in child router

[twhitbeck]

I set up an example of this at https://github.com/twhitbeck/nested-router-example.

The href for the links to components one and two are .undefined/one and .undefined/two.

The problem is that routerLink is attempting to build the href url from parent router's previousSegment property which isn't set until finishNavigating is called.

[btford]

Thanks for filing this issue. It's something I'm aware of; #81 shows a test case for this.