[ADD] added rating, rating_project and rating_project_issue module

 - Task : https://www.odoo.com/web#id=8060&view_type=form&model=project.task
 - Pad : https://pad.odoo.com/p/r.2BmKqyvcwKbiXPRI

[IMP] Added option to install rating module under Project

[IMP] added template to display when customer rates the task/issue

[IMP] Improved template and code

[IMP] : rating , rating_project and rating_project_issue as per new api

[IMP]: rating template

[FIX] : test case failed

[IMP] : code
use name_get() instead of name, if the model don't have name field.
name_get() will return a tuple (id, rec_name) of the model, or a string (not sure). For the tuple, use the rec_name. If it return other thing, set name to res_model + '/' + res_id.
Store the field (store=True) to use it in the graph view.