Remove PublishLast/InitialValue

See https://github.com/ReactiveX/RxJava/issues/1785
Fix for #1791 - don't retry (subscribe) to source if child has unsubscribed.
Take Unsubscribes Before OnNext

To prevent issues such as https://github.com/ReactiveX/RxJava/issues/1791
Merge pull request #1793 from benjchristensen/1791_first_with_retryWhen

Take/Redo Unsubscribe
1.0.0-rc.8
Merge pull request #1788 from benjchristensen/1785-remove-publish-overloads

Remove PublishLast/InitialValue
Improve TestSubject Javadoc

As per https://github.com/ReactiveX/RxJava/issues/1759
Merge pull request #1796 from benjchristensen/testsubject-javadoc

Improve TestSubject Javadoc