refactor graphscontroller for maintainability

It should also increase the readability.
add zoom and move capabilities to graphs

This adds zoom and move capabilities to the graph display for logics and
ontologies. Zoom can be performed by using the scroll-wheel of the mouse
or utilizing the slide-feature of a trackpad. Move can be performed by
doing a left-mouse-click and dragging and dropping the image.
extract graph marker-creation into function.
refactor label-functions for non-explicit return

Use conditional expression 'magic' instead of using multiple line if and
explicit return calling.
extract template name in graphs into function.
refactor readability of function(-calls).
fix indentation/dot-syntax in graphs-code.
use d3 instead of jquery in graphs where feasible.
remove (now) obsolete add/removeClass functions.
remove unnecessary explicit return-call.
fix anchor-urls for graph-depth representation.
optimize js graphs-uri determination.
fix asynchronous graph-load code.
use scrollbar for long graph-context information.
obey hound.
Merge pull request #1124 from ontohub/308-add_zoom_and_move_to_graphs

308 add zoom and move to graphs