Fix argparse runtime variable

It's args.time, not args.Runtime.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Deal with live collection better

Clear the trace buffer after we enable our events so we have a nice clean slate.
Also remember to turn off our events once we've stopped collecting if we've set
a time limit.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>