CompositeSubscription

- remove now also unsubscribes the removed subscription
- added clear method
Unsubscribe Idempotence Test
Merge pull request #477 from benjchristensen/subscription-bugfixes

CompositeSubscription bugfixes
[Gradle Release Plugin] - pre tag commit:  '0.14.9'.
[Gradle Release Plugin] - new version commit:  '0.14.10-SNAPSHOT'.
Version 0.14.9