[DAEMON-254] Add opt-in for telemetry on first run

When the daemon is first run, we need to prompt the user to opt-in/out of telemetry. Right now, it's implicitly enabled, but can be disabled by running appcd config telemetry.enabled false. This opt-in code block would go in appcd's [cli.js](https://github.com/appcelerator/appc-daemon/blob/master/packages/appcd/src/cli.js).