3291 follow-up (#3323)

* changelog: use issue number instead of PR number

* follow up to #3291

- rpc/test/helpers.go add StopTendermint(node) func
- remove ensureDir(filepath.Dir(walFile), 0700)
- mempool/mempool_test.go add type cleanupFunc func()

* cmd/show_validator: wrap err to make it more clear

node/node.go

@@ -793,6 +793,11 @@ func (n *Node) ProxyApp() proxy.AppConns {
 	return n.proxyApp
 }
 
+// Config returns the Node's config.
+func (n *Node) Config() *cfg.Config {
+	return n.config
+}
+
 //------------------------------------------------------------------------------
 
 func (n *Node) Listeners() []string {