PR review fixups on config options

cmd/vetinari-server/config.json

@@ -4,7 +4,7 @@
 		"tls_cert_file": "../../fixtures/ca.pem",
 		"tls_key_file": "../../fixtures/ca-key.pem"
 	}
-	"signingservice":{
+	"trust_service":{
 		"type": "local"
 		"hostname": ""
 		"port": ""

config/config.go

@@ -9,7 +9,7 @@ import (
 // all other configuration is namespaced under
 type Configuration struct {
 	Server       ServerConf       `json:"server,omitempty"`
-	TrustService TrustServiceConf `json:"signingservice,omitempty"`
+	TrustService TrustServiceConf `json:"trust_service,omitempty"`
 }
 
 // ServerConf specifically addresses configuration related to
@@ -25,8 +25,8 @@ type ServerConf struct {
 // `remote` will be used for
 type TrustServiceConf struct {
 	Type     string `json:"type"`
-	Hostname string `json:"hostname"`
-	Port     string `json:"port"`
+	Hostname string `json:"hostname,omitempty"`
+	Port     string `json:"port,omitempty"`
 }
 
 // Load takes a filename (relative path from pwd) and attempts