Add edot to show

[nathanielc]

Adds the throughput number to the DOT ouput of the kapacitor show command. This way you can get a quick glance without having to store and then query the internal stats.

Example DOT output:

digraph udp_drop {
stream0 -> stream1 [label="63921"];
stream1 -> groupby2 [label="143"];
groupby2 -> derivative3 [label="143"];
derivative3 -> window4 [label="142"];
window4 -> map5 [label="2"];
map5 -> reduce6 [label="2"];
reduce6 -> alert7 [label="2"];
}

Read as 63921 points have been sent from stream0 to stream1. In this case meaning that the dbrp of the task has received 63921 points. Only 143 points where passed from stream1 to groupby2 meaning that only 143 points matched the from and where conditions of the task.

These throughput numbers are only displayed if the task is executing.