let browser generate content-type for sending form-data (#1327)

* let browser generate content-type for sending form-data

* tell jquery.ajax to not set default content-type

* fix typos

fix #1122 fix #1309 fix #1234

Author: thenewvu

template/src/send_sample_request.js

@@ -140,10 +140,12 @@ function sendSampleRequest (group, name, version, method) {
     }
     requestParams.data = formData;
     requestParams.processData = false;
-    // GET and DELETE methods do not need content-type
-    if (method.toLowerCase() === 'get' || method.toLowerCase() === 'delete') {
-      delete requestParams.headers['Content-Type'];
-    }
+    // With no content-type header, browser will know it needs to generate a proper content-type for
+    // the form data when sending it. Fix #1122
+    delete requestParams.headers['Content-Type'];
+    // As of jQuery 1.6 you can pass false to tell jQuery to not set any content type header.
+    // https://api.jquery.com/jquery.ajax/
+    requestParams.contentType = false;
   }
 
   requestParams.type = method;