[REEF-55]: Delayed creation and upload of the global.jar file until the first Evaluator submission on YARN.

  * Added the `GlobalJarUploader` class which performs the creation and upload. It is a `Callable` such that we can move this to a thread in a future version
  * Moved the actual upload logic from `EvaluatorSetupHelper` to `UploaderToJobFolder`

JIRA:
  [REEF-55]: https://issues.apache.org/jira/browse/REEF-55