[age] aggregates/:check_name age filter parameter

      Sensu aggregates are "lazy", as they have no concept of "complete".
      This commit adds the age filter parameter, making it easier to grab a recent & most likely "complete" aggregate.
      The age parameter is intended to be used in combination with limit.

      eg. aggregate/redis_stunnel?limit=1&age=20
      ["1361428740"]

      This is a MoPub sponsored feature!

      /info "health" has been removed in favour of "rabbitmq" & "redis" "connected".
      The health filter has been removed.