Introduce callback "after-animation" to ngInclude

The after-animation-callback can be used to hook into the rendering of the ngInclude-directive. This is useful in case the client wants to restore a scrolling-position after the view has been rendered.

This can be used as a generalization of the anchorscroll, which can only scroll to a defined anchor in the document. 

The usecase which led to the development of this pull-request contained the need to scroll to a specific numer of pixels, which could only be realized by hooking into the after-animation event and exposing it to the client.
Why does this change need to be part of this commit?