Add ability to aggregate packets for sending

[jjofseattle]

This ports the functionality from https://github.com/msiebuhr/node-statsd-client for aggregated packets.

It shows great performance improvement. I ran perfTest/test.js to measure the time required of sending out 100,000 packets. A buffer size of 1200 is 5 times faster than no buffering. ==> node test.js 0 2143 2126 2186 2281 2487 1941 3006 2026 2909 2042 2049 ^C

==> node test.js 1200 395 389 385 388 393 389 390 388 389 391 388 389 ^C

==> node test.js 200 757 794 763 814 772 799 782 779 785 815 ^C

[allenarthurgay]

g2g

[jlutzhbo]

@devdazed @eexit Can we get a signoff on this PR please and get this merged in? Thanks!