Fix non-deterministic unit test

- the latch was before onError is called
- use BlockingObservable and expect the IllegalArgumentException to be thrown
Merge pull request #473 from benjchristensen/fix-nondeterministic-unit-test

Fix non-deterministic unit test
BugFix: Reduce an empty observable

This fixes issue https://github.com/Netflix/RxJava/issues/423

The fix is based on this comment by @headinthebox: https://github.com/Netflix/RxJava/issues/423#issuecomment-27642532
Merge pull request #474 from benjchristensen/issue-423-reduce-empty-observable

BugFix: Reduce an empty observable
Additional unit test for reduce
Merge pull request #475 from benjchristensen/issue-423-reduce-empty-observable

Additional unit test for reduce