Return 503 error when UM is not ready
Return 503 error when UM is not ready

felipevicens/son-gkeeper,felipevicens/son-gkeeper,jbonnet/son-gkeeper,dang03/son-gkeeper,sonata-nfv/son-gkeeper,jbonnet/son-gkeeper,sonata-nfv/son-gkeeper,jbonnet/son-gkeeper,jbonnet/son-gkeeper,felipevicens/son-gkeeper,sonata-nfv/son-gkeeper,dang03/son-gkeeper,dang03/son-gkeeper,dang03/son-gkeeper,sonata-nfv/son-gkeeper,felipevicens/son-gkeeper