def stats(type=nil)
      type = nil if ![nil, :items,:slabs,:settings].include? type
      values = {}
      ring.servers.each do |server|
        values["#{server.name}"] = server.alive? ? server.request(:stats,type.to_s) : nil
      end
      values
    end
def stats(type=nil)
      type = nil if ![nil, :items,:slabs,:settings].include? type
      values = {}
      ring.servers.each do |server|
        values["#{server.name}"] = server.alive? ? server.request(:stats,type.to_s) : nil
      end
      values
    end
Collect the stats for each server.
 You can optionally pass a type including :items, :slabs or :settings to get specific stats
 Returns a hash like { 'hostname:port' => { 'stat1' => 'value1', ... }, 'hostname2:port' => { ... } }