INT-2269 Add ReplyChannelRegistry

Allows reply channel resolution after a message has been serialized
somewhere in a flow. Previously, the reply channel was lost.

With this change, the reply channel can be registered and the header
becomes a string (channel name) that can be serialized.

JIRA: https://jira.springsource.org/browse/INT-2269

INT-2269 Rename Registry to HeaderChannelRegistry

- Extract interface
- DefaultHeaderChannelRgistry

INT-2269 Polishing; PR Comments

- Add errorChannel registration as well.

INT-2269 HeaderChannelRegistry - Fix

The internal BridgeHandler in MessagingGatewaySupport did not have
a channel resolver. When a reply was explicitly routed to the gateway's
reply channel, the String representation of the reply channel could
not be resolved to a channel.

Set the BeanFactory on the bridge handler.

Add tests.

INT-2269 HeaderChannelRegistry - Fix JMS/Enricher

The JMS inbound gateway and ContentEnricher instantiate a
MessagingGatewaySupport internally it does not get a
reference to the BeanFactory. This means that the internal
BridgeHandler cannot resolve the String representation of
the reply channel to a channel.

Make ChannelPublishingJmsMessageListener BeanFactory aware, and
propagate the bean factory to the MGS.

Set the MGS bean factory in the ContentEnricher (which is already
BFA).

INT-2269: Polishing