Resolve "GetMongoConnection() doens't return error in failure state"

controller/app/Store.go

controller/nucleus/database/mongo-connection.go

controller/nucleus/databaseNetworkElementStore.go

controller/nucleus/databasePluginStore.go

controller/nucleus/databasePndStore.go

controller/rbac/databaseRoleStore.go

controller/rbac/databaseUserStore.go

controller/topology/nodes/nodeStore.go

controller/topology/ports/portStore.go

controller/topology/routing-tables/routingTableStore.go

controller/topology/topologyStore.go