Added update check data test coverage
Added update check data test coverage

refs https://github.com/TryGhost/Team/issues/728

- This is a continuation of the test coverage for the UpdateCheckService.
- Covers a basic check for what kind of data is sent from the service to external analytics

ErisDS/Ghost,ErisDS/Ghost,ErisDS/Ghost,e10/Ghost,TryGhost/Ghost,TryGhost/Ghost,janvt/Ghost,TryGhost/Ghost,janvt/Ghost,e10/Ghost