INT-3113: Use Lettuce Redis Client

* Ensure close connections after tests
* Remove `Thread.sleep` where it is possible

JIRA: https://jira.springsource.org/browse/INT-3113

INT-3113: Improve `RedisAvailableRule`

* Upgrade to Spring-Data-Redis-1.1.0
* Change Redis port to default one - 6379

Polish - add smart delay to SubscribableRedisChannelTests.pubSubChannelTest
INT-2629 Extract Gateway Argument Mapping Strategy

https://jira.springsource.org/browse/INT-2629

Strategy for mapping gateway methods to map method arguments
to a message.

Default strategy works as today, but pluggable using attribute
'mapper' on <gateway/>.

A custom mapper should implement InboundMessageMapper<MethodArgsHolder>

where the MethodArgsHolder contains the Method object and the argument
values.

When using a custom mapper, the mapper is entirely responsible for
creating the Message - therefore 'payload-expression' attributes
and <header/> elements are not allowed.
INT-2629 Polishing - Javadocs