Ensuring Runnables posted with delay to a Handler are removed when unsubscribed.

This patch ensures the delayed runnables posted to a Handler are properly
removed when Subscription.unsubscribe() is called on the Observable.

The original code returns the subscription from schedule() but is not used
by the callers who instead add the Worker itself as a subsciption.

Signed-off-by: David Marques <dpsmarques@gmail.com>
Using a ScheduledAction in order to ensure correct subscription behaviour.

Signed-off-by: David Marques <dpsmarques@gmail.com>
Adding ScheduledSubscription to parent in order to properly chain unsubscribe.

Signed-off-by: David Marques <dpsmarques@gmail.com>
Using the correct code style for variable name and removing unused imports.

Signed-off-by: David Marques <dpsmarques@gmail.com>
Merge pull request #1321 from dpsm/master

Ensuring Runnables posted with delay to a Handler are removed when unsub...