refactor($autoScroll): rename to $anchorScroll and allow disabling auto scrolling (links)

Now, that we have autoscroll attribute on ng:include, there is no reason to disable the service completely, so $anchorScrollProvider.disableAutoScrolling() means it won't be scrolling when $location.hash() changes.

And then, it's not $autoScroll at all, it actually scrolls to anchor when it's called, so I renamed
it to $anchorScroll.