[crm] implementation planner

- Task: https://www.odoo.com/web/#id=8592&view_type=form&model=project.task&menu_id=3942&action=327
- Pad: https://pad.odoo.com/p/r.4BHh6hQdZ4GPR2qE
Create a PlannerManager class, which will contains init, start, fetch_application and on_menu_clicked. 
When this object is instanciate, it will load all the planners, and store them.
The on_menu_clicked function will take the menu id as argument, and will find in the list of planner which on to display. A PlannerLauncher will be created and display.

In web.Menu, override on_top_menu_click, and trigger an even ("top_menu_click" for example), and the id of the menu.

Override the Webclient class. In the start method, create an instance of PlannerManager. In show_application, call super(), then bind self.menu.on("top_menu_click", this.planner_manager, on_menu_clicked).