Set up default consumes/produces media types

See:

https://github.com/strongloop/loopback/issues/432
https://github.com/wordnik/swagger-js/issues/107

lib/class-helper.js

@@ -28,6 +28,8 @@ var classHelper = module.exports = {
       basePath: opts.basePath,
       resourcePath: urlJoin('/', opts.resourcePath),
       apis: [],
+      consumes: aClass.http.consumes || opts.consumes,
+      produces: aClass.http.produces || opts.produces,
       models: modelHelper.generateModelDefinition(aClass.ctor, {})
     };
   },

lib/swagger.js

@@ -7,12 +7,10 @@ module.exports = Swagger;
 /**
  * Module dependencies.
  */
-var debug = require('debug')('loopback:explorer:swagger');
 var path = require('path');
 var urlJoin = require('./url-join');
 var _defaults = require('lodash.defaults');
 var classHelper = require('./class-helper');
-var modelHelper = require('./model-helper');
 var routeHelper = require('./route-helper');
 
 /**
@@ -28,6 +26,9 @@ function Swagger(loopbackApplication, swaggerApp, opts) {
     swaggerVersion: '1.2',
     basePath: loopbackApplication.get('restApiRoot') || '/api',
     resourcePath: 'resources',
+    // Default consumes/produces to application/json
+    consumes: ['application/json'],
+    produces: ['application/json'],
     version: getVersion()
   });