Updated policy module from oslo-incubator

Updated policy module from oslo-incubator

Common policy has not been synced with oslo-incubator for a
long time and is seriously outdated.

This change pulls in fresh code from oslo-incubator which
introduces the Enforcer class to replace the old check function.

Rewrite neutron.policy using naming conventions and approach
that was set in Nova and amend related unit tests.
Remove neutron.common.exceptions.PolicyNotAuthorized and switch
to neutron.openstack.common.policy.PolicyNotAuthorized.
Drop Neutron specific policy_file option since now it is defined
in oslo-incubator policy module.

Change log:
4ca5091 Fixes nits in module policy
262fc82 Correct default rule name for policy.Enforcer
9e8b9f6 Minor fixes in policy module
6c706c5 Delete graduated serialization files
5d40e14 Remove code that moved to oslo.i18n
aebb58f Fix typo to show correct log message
bb410d9 Use MultiStrOpt for policy_dirs
33f44bf Add support for policy configration directories
2b966f9 Fix deletion of cached file for policy enforcer
238e601 Make policy debug logging less verbose
fe3389e Improve help strings
15722f1 Adds a flag to determine whether to reload the rules in policy
5d1f15a Documenting policy.json syntax
fcf517d Update oslo log messages with translation domains
e038d89 Fix policy tests for parallel testing
0da5de6 Allow policy.json resource vs constant check
e4b2334 Replaces use of urlutils with six in policy module
8b2b0b7 Use hacking import_exceptions for gettextutils._
0d8f18b Use urlutils functions instead of urllib/urllib2
12bcdb7 Remove vim header
9ef9fec Use six.string_type instead of basestring
4bfb7a2 Apply six for metaclass
1538c80 ConfigFileNotFoundError with proper argument
33533b0 Keystone user can't perform revoke_token
64bb5e2 Fix wrong argument in openstack common policy
b7edc99 Fix missing argument bug in oslo common policy
3626b6d Fix policy default_rule issue
7bf8ee9 Allow use of hacking 0.6.0 and enable new checks
e4ac367 Fix missing argument bug in oslo common policy
1a2df89 Enable H302 hacking check
7119e29 Enable hacking H404 test.
6d27681 Enable H306 hacking check.
1091b4f Reduce duplicated code related to policies

Closes-Bug: #1288178
Change-Id: I87ee30e2b64ec6b07faa84a231fd5f7eb925d501