feat(resize): ability to resize shapes

see bpmn-io/bpmn-js#140
feat(overlay): reposition overlay on shape.resize

see bpmn-io/bpmn-js #140
improve(resize): correctly change non diagram visuals on resize.undo

see bpmn-io/bpmn-js #140
improve(contextpad): increase gap between shape and context pad

related bpmn-io/bpmn-js #140
improve(resize): resize.undo / resize visual

related bpmn-io/bpmn-js#140