Add option to spit out tracefile, kill totalSleep

Easier to debug what latencytop is doing if it saves the output from a live run
into a file for later processing.  Also kill totalSleep because it is
misleading, saying we slept for 200 seconds when we only ran for 5 seconds.

Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Add an option to collapse processes by their name

This is usefull when trying to debug a problem with a large multi-threaded
application.  This will collapse all events for the given process into one big
process so you can have an aggregate of all of the pids and what they are doing.

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