Add find_stale_locks()

Signed-off-by: Zack Cerza <zack@redhat.com>
PEP-8 fixes

Signed-off-by: Zack Cerza <zack@redhat.com>
Port to docopt

Signed-off-by: Zack Cerza <zack@redhat.com>
Add teuthology-nuke --stale

Signed-off-by: Zack Cerza <zack@redhat.com>
Remove redundant read_config() call

Signed-off-by: Zack Cerza <zack@redhat.com>
Merge pull request #390 from ceph/wip-nuke-stale

teuthology-nuke --stale