SERVER-13712 smoke.py --clean-every=N option

(cherry picked from commit 8cd645a8fa0cce6313c4a15e4f3ec4fd8ac2787e)
SERVER-13712 cleanbb should clean entire /data/db dir

Invoke cleanbb via function call, not subprocess.

clean_dbroot() now cleans entire /data/db if --with-cleanbb specified,
including periodic cleanups.

(cherry picked from commit ab47b0b217ab40971a928bbe3d98bd315bbba716)
SERVER-13712 fix fedora8 builders (python 2.5.1)

(cherry picked from commit 630944421eebbbdbde600b6294e28ec992fc3fba)