XenAPI: Always update proxy settings
XenAPI: Always update proxy settings

If a user wants to re-use an xva just with different proxy settings, he
can now do it, as this change will always update /etc/apt/apt.conf to
reflect the settings in the user's localrc.

Change-Id: I8a6e9c88304bc887ea8269d946e89a5ba258b126

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