ignore errors if 'ps aux' fails

Signed-off-by: Alfredo Deza <alfredo.deza@inktank.com>
Merge pull request #306 from ceph/wip-9024

ignore errors if 'ps aux' fails
Import teuthology tasks (master branch)

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Merge branch 'teuth_master' into tasks_master
Update module references

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>