[IMP] addons: search view cleaning / improvements due to the new search view display
Merge pull request #675 from odoo-dev/master-search_view-crm-tde

[IMP] addons: search view cleaning / improvements due to the new search view display. Changes have been done in the main addons: crm, account, project, project_issue, hr_recruitment, purchase, sale.

Main changes :
- removed most of group_by in classic views (as most of them are usefull in a report view)
- removed all group_by in report views (as the new graph view allow to group on every field, no need to declare them)
- added some custom filters in various addons to help the user experience
- removed some useless icons / helps