INT-3014/INT-3015/INT-3016 Add Redis Channel Adapters

This basically is just copy from the respective code from Spring XD. This PR is meant to satisfy the minimum requirements to solve *Spring XD* issue - https://jira.springsource.org/browse/XD-49

More polishing and and improvements will be done using follow-up Jira - see: https://jira.springsource.org/browse/INT-3017