Sync latest Oslo

Sync from oslo-incubator commit 46f2b697b6aacc674bc040a8751997ed70490d1a

Major changes of the import are related to update policy module:
0da5de6b54 Allow policy.json resource vs constant check
5d1f15a778 Documenting policy.json syntax
33533b0d97 Keystone user can't perform revoke_token

Most changes are style-related topics:
* Improve Python3 compatibility
* Remove vim modelines
* Support Per-log-level logging translations

Closes-Bug: #1296337
Change-Id: I09f61b10b1b36015d248de25c5c6ed994717a565
Merge "Sync latest Oslo"