Return a new BufferedClient
addr is a string of the format "hostname:port", and must be parsable by net.ResolveUDPAddr.
prefix is the statsd client prefix. Can be "" if no prefix is desired.
flushInterval is a time.Duration, and specifies the maximum interval for packet sending. Note that if you send lots of metrics, you will send more often. This is just a maximal threshold.
flushBytes specifies the maximum udp packet size you wish to send. If adding a metric would result in a larger packet than flushBytes, the packet will first be send, then the new data will be added to the next packet.
If flushBytes is 0, defaults to 1432 bytes, which is considered safe for local traffic. If sending over the public internet, 512 bytes is the recommended value.