Adding initial page feature

Hi there,

I work at Lumis [http://www.lumis.com.br] and here we'll start to use a fork of your code to our publications viewer app, whose nickname is Poligno. We found useful to set an initial scroll to an element, so I'm sending you this pull request to thank you for your code and collaborate too.

Best regards,
=P
One more thing. This assumes that we are using vertically stacked element. Whereas vs-repeat also supports scrolling horizontally. Instead of referencing `scrollTop` use the `scrollPos` variable that i declare in the linking function.