Zip with iterable, removed old aggregator version and updated tests

[akarnokd]

Listed in #653.

[cloudbees-pull-request-builder]

RxJava-pull-requests #656 SUCCESS
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[benjchristensen]

These are instance methods, none of our zip operators are at the instance level. I would have thought we'd add the zip overloads with Iterable to match the existing static ones?

[akarnokd]

I went according to #653 where there was 2 zip overloads without strike-through.

[benjchristensen]

Agreed on the overloads, but they should be static, correct?

[akarnokd]

No. The intention was to chain them to an existing observable:

Observable.from(1, 2, 3).zip(Arrays.asList(4, 5, 6), (a, b) -> a * b);

[benjchristensen]

Makes sense, wasn't sure as it was different than all the other zip methods.

Thanks for confirming.