function RedisProbe() {
  Probe.call(this, 'redis');
}
Probe to instrument the redis npm.

Events are fired for calls to the basic commands either in upper or lower case
but are always reported as lower case to keep the two sets of events consistent.

Calls to batch.exec() and multi.exec() are also instrumented. Their events are
batch.exec and multi.exec to ensure they can be separately tracked.