Minor client changes.

1) Modified RxClientImpl.connect() to do a take(1) on the underlying source so that in no case it will emit two onNext().
2) Modified RequestProcessingOperator to use SubscriptionList instead of CompositeSubscription. Instead of creating a new subscription on every onNext(), it is done once and used by the subscriber.
3) Provided an override to remove all connection pooling for a client.
Updated Changes.md with maven artifact links.
Adding release 0.3.6 to Changes.md
Removing infinite waits from tests.

Many test cases were doing an infinite wait for the mock server to shutdown. This was more required when the servers were not using ephemeral ports.
Introduced a method of time wait on RxServer and using that method in test.
Removing method deprecated in rxjava-0.0.19.

- toBlockingObservable() is deprecated in favor of toBlocking()
- SubscriptionList class is moved to rxjava util pkg.
Merge pull request #133 from NiteshKant/master

Minor client changes.