Update summarize_timer_intervals.py for Python 3
Update summarize_timer_intervals.py for Python 3

Avoid using has_key and run the subprocess.check_output result through
.decode() before printing.

ariccio/UIforETW,google/UIforETW,google/UIforETW,ariccio/UIforETW,google/UIforETW,ariccio/UIforETW,google/UIforETW,ariccio/UIforETW