Feature/request arguments

A Controller now keeps its current request arguments and its referrers request arguments. 
Thus the view can pass this arguments to another view, which in turn can decide to render a back link with the referrer arguments. 
Currently we use it to get back to a filtered list view or search result view from the show view of positions.

Unfortunatly we ar not able to restore the current page of the pagination widget. The widget controller works with an internal argument @widget_<number of widget> which we can not pass back due of the at sign.