Add oslo.i18n lib to requirements
Add oslo.i18n lib to requirements

The oslo.i18n lib provides i18n functions that were provided by
oslo-incubator's gettextutils module.

Implements blueprint sahara-oslo-i18n

Change-Id: Ibf360b1762bdb3c76b2176db541827367ff922b4

openstack/sahara,mapr/sahara,xme1226/sahara,ekasitk/sahara,tellesnobrega/sahara,citrix-openstack-build/sahara,esikachev/scenario,zhangjunli177/sahara,henaras/sahara,esikachev/sahara-backup,mapr/sahara,matips/iosr-2015,citrix-openstack-build/sahara,henaras/sahara,ekasitk/sahara,egafford/sahara,tellesnobrega/sahara,zhangjunli177/sahara,citrix-openstack-build/sahara,zhujzhuo/Sahara,bigfootproject/sahara,zhangjunli177/sahara,keedio/sahara,zhujzhuo/Sahara,matips/iosr-2015,xme1226/sahara,keedio/sahara,ekasitk/sahara,crobby/sahara,egafford/sahara,keedio/sahara,redhat-openstack/sahara,redhat-openstack/sahara,crobby/sahara,xme1226/sahara,bigfootproject/sahara,esikachev/sahara-backup,zhujzhuo/Sahara,esikachev/scenario,henaras/sahara,matips/iosr-2015,esikachev/sahara-backup,crobby/sahara,redhat-openstack/sahara,openstack/sahara,bigfootproject/sahara,esikachev/scenario,mapr/sahara