Create the ability for custom key binding to control the pomodor

    Expose the logic that is used in get_buttons
    
    Allow users to bind the logic used in get_buttons in their awesome
    config files. New functions for:
    
    * starting a new poomodoro
    * stopping a pomodo
    * pausing a pomodoro
    * increasing the pomodoro time
    * decreasing the pomodoro time
    
    were created and used in the old get_buttons