Sentinel LWRP

Note: The branch name is a misnomer and turned out to only cover sentinel work, and not slaveof master replication.

This is another step at integrating the work by @chrisroberts ( https://github.com/miah/chef-redis/pull/9 ) this adds a sentinel LWRP. I have little experience with actually using redis sentinels, but as far as I can tell this seems to work.

This also updates the default source install to 2.6.11