Revert "Exit when printing error about database config"
Revert "Exit when printing error about database config"

This reverts commit 2d7c346f0c8cefe622edc8fed47cc2782aeb9a9b.

Not setting DATABASE_TYPE is not a fatal error since it is
valid to create nodes which only run a subset of services,
and so a database may not be needed.

Change-Id: I7d957e628141ba333b6f38940b39845b18fba4df

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