Renamed the HelloREEF Job

this is part of #937, but not the full fix.
Results of code review with Shravan
Merge pull request #957 from Microsoft-CISL/weimer_937a

Renamed the HelloREEF Job
Merge pull request #954 from Microsoft-CISL/weimer_953

Introducing ContextRepresenters
Merge branch 'master' of https://github.com/Microsoft-CISL/REEF into weimer_763b
Code review with Shravan