Update Mockery dependency to 0.9.0

Changes since last pull request:
- against 4.1, not master
- change all the composer.json files

```
find -name composer.json | grep -v vendor | xargs sed -i
's,"mockery/mockery": "0.8.0","mockery/mockery": "0.9.0",'
```

Mockery 0.9.0 supports HHVM 2.4.0 - Laravel gets a 100% pass with it. Will
still fail on Travis, as they're running 2.3.