CombineLatest fix
Moved onError, onCompleted and cancel.unsubscribed outside the lock
New contrib module: rxjava-async-util

Home for async utility functions with juc.Future, Actions, Functions etc that don’t need to be in rxjava-core.

As per discussions at:

- https://github.com/Netflix/RxJava/pull/646#issuecomment-31147005
- https://github.com/Netflix/RxJava/pull/645#issuecomment-31146492
- https://github.com/Netflix/RxJava/pull/622#issuecomment-31144128
Manual merge of https://github.com/akarnokd/RxJava/commit/eee312a6ac41582e4efe3daac3dfcd0385359d25

- To clean up the pull request I cherry picked the single commit with actual changes to avoid the merges that affected lots of other files.
- The original commit also included conflicting and unrelated changes to Observable and ObservableTests that I skippedManual merge of https://github.com/akarnokd/RxJava/commit/eee312a6ac41582e4efe3daac3dfcd0385359d25
Merge pull request #707 from benjchristensen/rxjava-async-util-module

Merge of rxjava-async-util
Merge branch 'CombineLatestFix' of github.com:akarnokd/RxJava into combine-latest
Manual Merge of Pull #616

Manual merge of https://github.com/Netflix/RxJava/pull/616

- remove use of SingleAssignmentSubscription
- suppress warnings
Merge pull request #708 from benjchristensen/combine-latest

Combine latest fix
Lotsa javadoc improvements
* diagrams for previously-undiagram'd methods
* links to wiki docs where available
* standardizing format & nomenclature
Merge pull request #709 from Netflix/docs

Lotsa javadoc improvements
Created new wiki page for the operators in the Async class
...adjusted javadoc links accordingly
...added new sections for previously un-wiki-documented operators in Async
...added links to those in javadocs
Merge pull request #710 from Netflix/docs

Created new wiki page for the operators in the Async class
Update Scheduler Tests for Recursion and Common Testing
Fix Deprecated Method Call
Memory Leak Tests

NewThreadScheduler is working, the other two are not so commented out for now until fixed.
Fix Memory Leak in NewThreadScheduler Recursion

- the Action0 method did not have a leak
- the Func2 method on inner scheduler recursion did have a leak
Scheduler Unit Tests

- passing for all but ExecutorScheduler
ExecutorScheduler Memory Leak Fix

- new InnerExecutorScheduler and childSubscription
- improvements to unit tests
CurrentThreadScheduler Memory Leak Fixed

- Current/Immediate/NewThread/Executor Schedulers are passing unit tests
- Current/NewThread/Executor Schedulers do not leak memory on the recursion test (Immediate can’t be used for recursion otherwise it stack overflows)
Small ObserveOn Improvements

- use Long instead of Int so we don’t overflow
- migrate from deprecated method