Open to option to enable telemetry by option?

[travisgriggs]

Every tortoise/mqtt connection spins up a telemetry process. There's not much to it. It periodically (30seconds I think) samples the socket and updates total sent/receive bytes. I have no use for this. But I spin up lots of connections, so all of those little processes add up as far as memory consumption.

Right now, I'm just commenting out the child_spec entry in my local deps directory and things work fine. Would there be openness to making this an option of the connection (defaulted to true of course so behavior stays same)? If so, I'll do a pull-request, otherwise, I'll just keep hacking it locally.

[jfcloutier]

Please go ahead with the PR. Thanks!