Change zip method signature from Collection to Iterable

Fix javadoc typos.
Merge pull request #370 from benjchristensen/zip-collection-to-iterable

Change zip method signature from Collection to Iterable
Operator: Retry

https://github.com/Netflix/RxJava/issues/72
Merge pull request #371 from benjchristensen/retry

Operator: Retry
Merge branch 'master' of github.com:Netflix/RxJava into idiomaticscala