[ADD]Hr material:added new module hr_material,which allows you to easily...

... keep track of office materials.

- Task: https://www.odoo.com/web#id=6897&view_type=form&model=project.task
- Pad: https://pad.odoo.com/p/r.JyyLhFD93zvKcCbu
I would put two methods, one _compute_material_count and one _compute_maintenance_count. Put them below their related field definition, so that the reading comes in a logic order.