Re-order stack.sh 1: sanity checks
Re-order stack.sh 1: sanity checks

Part 1 of a series

Re-order the setup and check bits in the top portion of stack.sh to
have a logical flow with similar things done together.

No behaviour changes are intended aside from the order of execution.
Any such changes are bugs.

* Do sanity checks that have no configuration needs earlier
* Do supported distro check earlier

Change-Id: I7d15bac199d6c4382d4a4d222784d34f2707da56

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