Clean up old power manager files
Clean up old power manager files

Added command to chromeos-cleanup-logs to clean up old files in
/var/log/power_manager.

BUG=9123
TEST=Create some "old" files using "touch -t".  Have their mod. times
extend over a range, from present to 10 days ago.  These files must be
in /var/log/power_manager and must begin with "power".  Run the script.
All files older than 7 days should be gone.  All files newer than that
should remain.

Change-Id: I8a048b00995ef39b22ee8558b1df95a27f94b955
Signed-off-by: Simon Que <sque@chromium.org>

Review URL: http://codereview.chromium.org/5151007

joshfire/chromiumos-platform-init