Category, Attribute and Family jobs

| Q                    | A
| -------------------- | ---
| Bug fix?             | N
| New feature?         | Y
| Behat pass?          | ~
| Tests pass?          | Y
| Checkstyle issues?   | ~
| PMD issues?          | ~
| Changelog updated?   | ~
| DB schema updated?   |
| Migration script?    |
| Doc PR               |
should be decoupled into 2 classes : 
* the WS able to connect to the Sylius API 
* the abstract writer that uses this WS