Added possibility of using $MIRROR_POSTFIX variable
Added possibility of using $MIRROR_POSTFIX variable

related with: https://review.fuel-infra.org/#/c/4405/

Change-Id: I4ee6592a8266fd94ca951bea4d7d5d8071af60da

zhaochao/fuel-main,eayunstack/fuel-main,dancn/fuel-main-dev,ddepaoli3/fuel-main-dev,teselkin/fuel-main,teselkin/fuel-main,AnselZhangGit/fuel-main,dancn/fuel-main-dev,teselkin/fuel-main,SergK/fuel-main,ddepaoli3/fuel-main-dev,SergK/fuel-main,stackforge/fuel-main,Fiware/ops.Fuel-main-dev,SmartInfrastructures/fuel-main-dev,ddepaoli3/fuel-main-dev,AnselZhangGit/fuel-main,eayunstack/fuel-main,AnselZhangGit/fuel-main,teselkin/fuel-main,dancn/fuel-main-dev,zhaochao/fuel-main,SmartInfrastructures/fuel-main-dev,huntxu/fuel-main,ddepaoli3/fuel-main-dev,SmartInfrastructures/fuel-main-dev,eayunstack/fuel-main,Fiware/ops.Fuel-main-dev,dancn/fuel-main-dev,huntxu/fuel-main,zhaochao/fuel-main,Fiware/ops.Fuel-main-dev,zhaochao/fuel-main,zhaochao/fuel-main,AnselZhangGit/fuel-main,SergK/fuel-main,stackforge/fuel-main,Fiware/ops.Fuel-main-dev,huntxu/fuel-main,SmartInfrastructures/fuel-main-dev,stackforge/fuel-main