Support Dogstatsd protocol 1.1

[blemale]

There is a new experimental Dogstatsd protocol (1.1) which supports sending multiple values in a single datagram.

This is supported since agent 7.25.0/6.25.0.

This evolution in the protocol allows clients to buffer histogram and distribution values and send them in fewer payload to the agent (providing a behavior close to client-side aggregation for those types).

[blemale]

If it is ok, I can come with a PR :)