radosgw-admin: Bug fixes for issue 4251.

Signed-off-by caleb.miles<caleb.miles@inktank.com>
Add timer.py and display summary info in run.py.

Signed-off-by: Warren Usui <warren.usui@inktank.com>
nuke: blow away /home/ubuntu/cephtest too

(along with /tmp/cephtest)

Signed-off-by: Sage Weil <sage@inktank.com>