movablePolygon and circleGraph onMove/onResize improvements

Summary:
adds dX, dY to movablePolygon.onMoveEnd()
adds newRadius, oldRadius to circleGraph.onResizeEnd()
adds cancel/overwrite semantics to circleGraph.onResize()

Test Plan: used in new transformations tool in perseus

Reviewers: alex

Reviewed By: alex

Differential Revision: http://phabricator.khanacademy.org/D4886