* The user can go to the settings application part and get back to pomodoro
* The pomodoro user can rewind the current pomodoro
* The pomodoro user can move next pomodoro or move previous pomodoro
* When the pomodoro user move the mouse hover a button, a tooltip with it's signification and the shortcut appears

[index.html]
  Add a toolbar that contains the button pomodoro-backward, pomodoro-rewind, pomodoro-forward
  Add title on the button

[PomodoroView]
  Add the methods pomodoroBackward, pomodoroForward, pomodoroRewind to control the execution.
  Modify render method to disable backward button if it's the first pomodoro

[PomodoroModel]
  Add a method isFirstPomodoro
  Add a method rewind, movePreviousStep