Updated fileutils and its dependencies

This is to avoid fileutils dependency on excutils that are now moved to
oslo.utils.

The following changes are included:

* neutron/openstack/common/__init__.py
  6b048e7 Let oslotest manage the six.move setting for mox

 * neutron/openstack/common/_i18n.py
  9ce1d96 Fix i18n import
  5d40e14 Remove code that moved to oslo.i18n

 * neutron/openstack/common/fileutils.py
  6ff6b4b Switch oslo-incubator to use oslo.utils and remove old modules
  2b966f9 Fix deletion of cached file for policy enforcer
  9c88dc3 file_open: fixed docstring to refer to open() instead of file()
  6c7407b fileutils: port to Python 3
  fcf517d Update oslo log messages with translation domains

 * neutron/openstack/common/log.py
  6c706c5 Delete graduated serialization files
  5d40e14 Remove code that moved to oslo.i18n
  6ff6b4b Switch oslo-incubator to use oslo.utils and remove old modules
  aa74411 log: add missing space in error message
  037dee0 Set stevedore log level to WARN by default
  37c0091 Add unicode coercion of logged messages to ContextFormatter
  6614413 Correct coercion of logged message to unicode
  1188d88 Except socket.error if syslog isn't running
  ac995be Fix E126 pep8 errors
  631f880 Set keystonemiddleware and routes.middleware to log on WARN level
  726d00a Adjust oslo logging to provide adapter is enabled for
  433fa0b Make logging_context_format_string optional in log.set_defaults
  ac92c06 Add default log level for websocket
  5fd77eb Ability to customize default_log_levels for each project
  4d9328c Python 3: enable tests/unit/test_log.py
  cb5a804 Move `mask_password` to strutils

Note: cb5a804 is partially included; that's ok because we don't use the
moved function in Neutron.

Change-Id: I3bfcaff2620b368d807e9468bb7abc01d6471661
Merge "Updated fileutils and its dependencies"