* Add BUILDORDER_REQUIRE_RESPONSIBLE setting
- If set, build orders must specify a responsible owner
* Add responsible required setting to other order models:
- PurchaseOrder
- SalesOrder
- ReturnOrder
* Add unit test
* Adjust unit tests
* Settings updates:
- Only check settings for global and user settings
- Plugin settings are not defined at run-time
* typo fix
* More spelling fixes
* Specify responsible owner pk