Use daemon flag only when USE_SCREEN=False
Use daemon flag only when USE_SCREEN=False

This patch removes the daemon option, when devstack is started
with USE_SCREEN=True.

Change-Id: Ib3b1c0b2abf9111b767b3d557dacdc7a89a38f59

innodee/openstackk,pacinete/devstack,dtroyer/devstack,affo/devstack,liuquansheng47/devstack,group-policy/devstack,bq-xiao/devstack,wenhuizhang/devstack,srics/devstack,prithivm/branch01,eshnil2000/devstack,herrsechs/devstack,bljgaurav/openstack-test,samgoon/devstack,olivierlemasle/devstack,prithivm/branch01,LoHChina/devstack,costingalan/devstack,mmasaki/devstack,vsham20/devstack,Mahito/devstack,HPCHub/devstack,affo/devstack,j4/devstack,mmasaki/devstack,varunarya10/devstack,upadhyay-prashant/devstack,noironetworks/devstack,noironetworks/devstack,mc2014/devstack,CloudServer/devstack,liuquansheng47/devstack,flavio-fernandes/devstack,vishnugonela/devstack,NaokiMiyata/devstack,mssumanth/devstack,ozamiatin/devstack,vsham20/devstack,nawawi/openstack,atulpatil301/devstack,nuxeh/devstack,pombredanne/devstack,bq-xiao/devstack,virtualopensystems/devstack,promptworks/devstack,neerja28/Devstack_GlusterFS,tianweizhang/devstack,Mahito/devstack,atulpatil301/devstack,j4/devstack,andrewrothstein/devstack,wenhuizhang/devstack,BSJAIN92/OpenStack,group-policy/devstack,costingalan/devstack,tianweizhang/devstack,BSJAIN92/OpenStack,bswartz/devstack,bigswitch/devstack,TwinkleChawla/devstack,thomasem/devstack,parul24/devstack,pombredanne/devstack,bigswitch/devstack,richliu/devstack,upadhyay-prashant/devstack,openstack-dev/devstack,pacinete/devstack,dirkmueller/devstack,TwinkleChawla/devstack,eharney/devstack,avvocatodemarchis/devstack,andrewrothstein/devstack,varunarya10/devstack,thomasem/devstack,dirkmueller/devstack,vishnugonela/devstack,LoHChina/devstack,nuxeh/devstack,avvocatodemarchis/devstack,pczerkas/devstack,rushiagr/devstack,mssumanth/devstack,samgoon/devstack,mc2014/devstack,pczerkas/devstack,openstack-dev/devstack,dtroyer/devstack,sc68cal/devstack,parul24/devstack,olivierlemasle/devstack,eharney/devstack,richliu/devstack,neerja28/Devstack_GlusterFS,promptworks/devstack,bswartz/devstack,nawawi/openstack,CloudServer/devstack,sequenceiq/devstack,NaokiMiyata/devstack,sc68cal/devstack,kplus/devstack-moonshot,ozamiatin/devstack,herrsechs/devstack,kplus/devstack-moonshot,flavio-fernandes/devstack,sequenceiq/devstack,rushiagr/devstack,bljgaurav/openstack-test,HPCHub/devstack