Sync request_utils module from oslo-incubator
Sync request_utils module from oslo-incubator

The request_utils module hasn't had a sync done since shortly
after the module was added.  This patch brings us up to date
with the latest oslo-incubator code.

This sync is needed to enable removal of the old gettextutils
and i18n code.

Current HEAD in OSLO:
---------------------
commit 36b0e8570b449129d6d474c03b02ceb62edb78df
Date:   Thu Dec 11 11:27:08 2014 +0100
We shouldn't replace `oslo-incubator` in comments

Changes being merged with this patch:
---------------------
5d40e143 - Remove code that moved to oslo.i18n
39625e18 - Set pbr 'warnerrors' option for doc build

Change-Id: Ib5b75d6ff38ff6f9571a0fdc30e854e046e66dd7

apporc/cinder,winndows/cinder,saeki-masaki/cinder,tlakshman26/cinder-new-branch,Akrog/cinder,Accelerite/cinder,duhzecca/cinder,manojhirway/ExistingImagesOnNFS,nexusriot/cinder,Paul-Ezell/cinder-1,eharney/cinder,duhzecca/cinder,JioCloud/cinder,julianwang/cinder,tlakshman26/cinder-new-branch,Datera/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,scality/cinder,dims/cinder,leilihh/cinder,tlakshman26/cinder-https-changes,Nexenta/cinder,nexusriot/cinder,bswartz/cinder,NetApp/cinder,rakeshmi/cinder,blueboxgroup/cinder,j-griffith/cinder,nikesh-mahalka/cinder,sasukeh/cinder,hguemar/cinder,mahak/cinder,nikesh-mahalka/cinder,abusse/cinder,julianwang/cinder,saeki-masaki/cinder,bswartz/cinder,Datera/cinder,CloudServer/cinder,potsmaster/cinder,CloudServer/cinder,phenoxim/cinder,NetApp/cinder,mahak/cinder,tlakshman26/cinder-bug-fix-volume-conversion-full,Hybrid-Cloud/cinder,blueboxgroup/cinder,cloudbase/cinder,phenoxim/cinder,manojhirway/ExistingImagesOnNFS,takeshineshiro/cinder,dims/cinder,ge0rgi/cinder,Accelerite/cinder,Nexenta/cinder,petrutlucian94/cinder,openstack/cinder,rakeshmi/cinder,hguemar/cinder,Akrog/cinder,leilihh/cinder,cloudbase/cinder,scality/cinder,winndows/cinder,sasukeh/cinder,Hybrid-Cloud/cinder,openstack/cinder,abusse/cinder,potsmaster/cinder,apporc/cinder,petrutlucian94/cinder,j-griffith/cinder,takeshineshiro/cinder,Paul-Ezell/cinder-1,JioCloud/cinder,eharney/cinder,scottdangelo/RemoveVolumeMangerLocks,scottdangelo/RemoveVolumeMangerLocks,tlakshman26/cinder-https-changes