Docs updated for image usernames
Docs updated for image usernames

Change-Id: I935baccea1e5ac39ce7e363bff29dab5ec80b7c3
Fixes: bug #1236334

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