Clean stale lockfiles on service startup : fixes bug 785955
Clean stale lockfiles on service startup : fixes bug 785955

Adds cleanup_files_locks() to nova/utils, which cleans up stale locks
left behind after process failures.

Adds a call to clean up locks on service startup for nova-api, nova-cert,
nova-compute, nova-network, nova-objectstore, and nova-scheduler.

Adds tools/clean_file_locks.py, which can be used to manually clean
stale locks.

Change-Id: I752e0b24d3c7fc5f1dc290da355cbd7f430789b8

hyakuhei/cleantox,emonty/oslo-hacking,hyakuhei/cleantox,zancas/hacking,openstack-dev/hacking,emonty/oslo-hacking,openstack-dev/hacking,zancas/hacking