Make nuke use its own logger

Signed-off-by: Zack Cerza <zack.cerza@inktank.com>
Remove needless arg from list_locks()

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

Currently implements killing suites-runs.

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