fix incorrect this
change model: TodoItem.uncomplete(), TodoList.completeAll()
"clear completed" button; "mark all as completed" button state; allow uncomplete all;
confirm the deletion if the item has children
Merge pull request #19 from olebedev/confirm

confirm the deletion if the item has children
Merge gritzko/master (fix conflict in view/TodoItemView.jsx)
Merge pull request #17 from abalandin/fix-selection

bugfixes: "clear completed" button, "mark all" button, selection style.
Merge olebedev/touch-tab (conflicts in view/TodoItemView.jsx)
change todo.appcache
Merge pull request #1 from abalandin/touch-tab

Touch tab merge