[RFR] Introduce edit-button and delete-button directives

- [x] Introduce edit-button and delete-button directives
- [ ] ~~add reference-link directive~~
- [x] add `view.listActions(['edit', 'delete']) helper
- [x] update documentation

Refs #121
What if we call `listActions` twice ? It'll add 2 column on the datagrid ?