[IMP] hr modules: needaction, subtypes and department-based improvements.

This commit prepares some cleaning in various hr-related modules that are
about to land in master. There are mainly improvements on subtypes. The
subtypes are now linked to department subtypes, allowing to follow some records
based on the department (like project/task/issue).
Merge branch 'master' of https://github.com/odoo/odoo into master-linux64