Also fix a bug where the trace command may capture the wrong file
if multiple trace file paths are in the Android log buffer.

Previously we found a lower bound timestamp for the trace path log
by running the date command on the device and parsing the result on
the host.  This could yield an inaccurate result if the device and
host are using different time zones.

The command will now obtain the most recent timestamp in the device's
time format by running logcat.