Remove `processutils` dependency on `log`

Currently, the processutils module depends on openstack.common.log. This
patch proposes to remove this dependency and use the standard library
logging module instead.

The downside of this patch is that it removes the dependency on the log
module but adds a new dependency on the strutils module because of the
`mask_password` call.

Change-Id: I245750f9f397a231891514f6ed1ea9626513cbbb
Merge "Remove `processutils` dependency on `log`"