INT-3177: generic RedisTemplate for PublishingMH

JIRA: https://jira.springsource.org/browse/INT-3177

* Change `RedisPublishingMessageHandler.StringRedisTemplate` to `RedisTemplate<?, ?>`
* Don't provide `serializer` to the `template`
* Use `serializer` directly for values which are not `byte[]`
* Add `RedisAvailableTests#awaitContainerSubscribed` for tests to avoid race conditions
* Refactor some tests
* Add test for `byte[]` payload
INT-3177: Generic RedisInboundChannelAdapter

Port from Spring XD: allow for `RedisInboundChannelAdapter`
to receive from Redis any object, not only String

* Make `serializer` property 'resettable' to `null`
* Change `RedisInboundChannelAdapterParser` to allow to apply
empty value from `serializer` attribute
* Add parser test and test for `byte[]` messages
INT-3177: Polishing and documentation

JIRA: https://jira.springsource.org/browse/INT-3033

* Add `topic-expression` to `<int-redis:outbound-channel-adapter>`
* Add tests and docs