Fix warning due to "HaveOccured" being deprecated
Fix warning due to "HaveOccured" being deprecated

```
WARNING: The HaveOccured matcher is deprecated!
We've corrected the spelling of "HaveOccured" to "HaveOccurred".
Update your package by running "gofmt -r 'HaveOccured() -> HaveOccurred()' -w *.go".
```

MeGaPk/goreq,sschepens/goreq,vvelikodny/goreq,franela/goreq,dickeyxxx/goreq,ryansb/goreq,ProjectFrank/goreq,evalphobia/goreq,gcnonato/goreq,appfront/goreq,CrowdSurge/goreq,admpub/goreq