Explicit support for DomainEventStreams that implement Closeable

Made sure all places where Axon reads a DomainEventStream are close when
the DomainEventStream implements Closeable.

Based on code provided by hovenko (https://github.com/AxonFramework/AxonFramework/pull/98),
which has been merged into the axon-2.0.x branch.

Issue #AXON-187 Fixed