Datagrid page size in user settings

__Tasks:__

- [ ] gather feedback for my changes

Depends on https://github.com/massiveart/husky/pull/427

__Informations:__

| Q             | A
| ------------- | ---
| Tests pass?   | yes
| Fixed tickets | fixes https://github.com/sulu-cmf/sulu/issues/636
| BC Breaks     | none
| Doc           | none
Wouldn't be something like `gridOptions.searchInstanceName = gridOptions.searchInstanceName || toolbarOptions.instanceName` shorter and more clear?