rbd: recognize 'randomize' parameter

randomize (default: false) randomizes xfstests test order.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
rbd: change test_script to run_xfstests_krbd.sh

Invoke run_xfstests.sh through a wrapper, which supplies an exclusion
list, in order to skip tests we don't want to run.

Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Merge pull request #267 from ceph/wip-runxfstests

wip-runxfstests

Reviewed-by: Josh Durgin <josh.durgin@inktank.com>