Squashed commit of the following:

commit 1b661f0a1b53693892d5af066d33f4cd3aa27de2
Author: Anders Wenhaug <wenhaug@stud.ntnu.no>
Date:   Mon Apr 14 11:33:10 2014 +0200

    Don't move images that is not visible at all. Look for images under document instead of under the element in focus.

commit 49fdf115c64fac88cd008439e00dfcbb6f1f2c79
Author: Anders Wenhaug <andersw@broadpark.no>
Date:   Fri Mar 7 20:54:04 2014 +0100

    Added option to hold shift while dragging an image to move it instead of resizing it. Solves issues with very big pictures by letting you view the entire picture, and not just the top left part of it.

    Fixed sometimes following image URL when releasing the mouse at the end of the move.

    Updated image hover text

    Added check to see if the image has moved so we don't break shift+click functionality (opens link in new window, at least in Chrome).

    Added a comment.

    Formatting.

    Added zIndex to movable images so they are displayed above the "Set a tag" buttons.

    Reworked how moving of images work to better support external calls of moveImage (as when keyboardNav wants to move the image).

    Added ability to move images with shift + [up|down|left|right] arrows.
Merge pull request #819 from gablank/master

Add image move support