Update composer.json

@jmeyo why we need to have dev-master instead of 1.1?

Not sure why, but I can't get composer working with 

```
syliyus 0.9, 
cmf-menu 1.0
knp-menu dev-master
 ```

when upgrading to sylius 0.10 this config would work, but for master in AAA, this won't work.