commit 08f096a2778a731c4de40c13edb1e7141f39a02b
author Sergiy Matusevych <motus@apache.org> Tue Oct 11 13:52:05 2016 -0700
committer Markus Weimer <weimer@apache.org> Fri Oct 14 16:53:15 2016 -0700
tree a4480659870ec842d6f855413a65869837d99584
parent 234eeba7de648d5f1dbed4246733f60df143bca7

[REEF-1615] Add unit tests and improve logging for `REEFEnvironment` functionality

This is work towards [REEF-1561](https://issues.apache.org/jira/browse/REEF-1561) *REEF as a library* project.

Some unit tests in `REEFEnvironmentFailDriverTest` are currently commented out due to the
[REEF-1637](https://issues.apache.org/jira/browse/REEF-1637) issue (Driver does not receive Evaluator heartbeats).

Summary of changes:
   * Create unit tests for failures on different stages of REEF Driver life cycle;
   * Create a version of `HelloREEF` example for `REEFEnvironment`;
   * Improve in `TestUtils` to handle in-process jobs;
   * Get rid of checkstyle warnings in `FailDriver`;
   * Comment out singleton assertion in `Evaluators`: it is no longer true in `REEFEnvironment` setting;
   * Add a TODO note for Evaluator singleton assertion;
   * Add `.toString()` methods to some events for better logging and debuggability;
   * Minor fixes to improve logging and code readability.

JIRA:
  [REEF-1615](https://issues.apache.org/jira/browse/REEF-1615)

Pull Request:
  This closes #1152