write git packet lines (for smart remote protocol)
var send = require'git-write-pkt-line'sendon'data'console.logdsendwrite'want 0000000000000000000000000000000000000000'
this module presents a
through stream; when written to it adds the appropriate
length header and newline ending. if an empty string or buffer is written, it will
send a git "flush packet", which is just a size-0 packet.