feat(keyboard): key bindings toggle tools

Closes #459

lib/features/keyboard/BpmnKeyBindings.js

@@ -16,13 +16,13 @@ function BpmnKeyBindings(keyboard, spaceTool, lassoTool, handTool, directEditing
       selection.select(elements);
     },
     spaceTool: function() {
-      spaceTool.activateSelection();
+      spaceTool.toggle();
     },
     lassoTool: function() {
-      lassoTool.activateSelection();
+      lassoTool.toggle();
     },
     handTool: function() {
-      handTool.activateHand();
+      handTool.toggle();
     },
     directEditing: function() {
       var currentSelection = selection.get();