getServicesConfig -> getServiceConfig

it gets setting of a single service. the settings API returns multiple
ones, so it makes sense to call that one getServicesConfig

src/services.js

@@ -3,7 +3,7 @@
 exports = module.exports = {
     getServices,
     getService,
-    getServicesConfig,
+    getServiceConfig,
     configureService,
     getServiceLogs,
     restartService,
@@ -363,7 +363,7 @@ function getServices(callback) {
     });
 }
 
-function getServicesConfig(id, callback) {
+function getServiceConfig(id, callback) {
     assert.strictEqual(typeof id, 'string');
     assert.strictEqual(typeof callback, 'function');
 
@@ -420,7 +420,7 @@ function getService(id, callback) {
         tmp.error = result.error || null;
         tmp.healthcheck = result.healthcheck || null;
 
-        getServicesConfig(id, function (error, service, servicesConfig) {
+        getServiceConfig(id, function (error, service, servicesConfig) {
             if (error) return callback(error);
 
             const serviceConfig = servicesConfig[name];
@@ -448,7 +448,7 @@ function configureService(id, data, callback) {
         return callback(new BoxError(BoxError.NOT_FOUND));
     }
 
-    getServicesConfig(id, function (error, service, servicesConfig) {
+    getServiceConfig(id, function (error, service, servicesConfig) {
         if (error) return callback(error);
 
         if (!servicesConfig[name]) servicesConfig[name] = {};