Add method to api for submitting forms

Some of our legacy endpoints expect this style rather than json.

Also clean up the way useCsrf works — don't always set json attribute to an empty object.

src/lib/api.js

@@ -18,7 +18,7 @@ module.exports = function (opts, callback) {
     defaults(opts, {
         host: process.env.API_HOST,
         headers: {},
-        json: {},
+        responseType: 'json',
         useCsrf: false
     });
 
@@ -33,6 +33,11 @@ module.exports = function (opts, callback) {
             .join(opts.uri.indexOf('?') === -1 ? '?' : '&');
     }
 
+    if (opts.formData) {
+        opts.body = urlParams(opts.formData);
+        opts.headers['Content-Type'] = 'application/x-www-form-urlencoded';
+    }
+
     var apiRequest = function (opts) {
         if (opts.host !== '') {
             // For IE < 10, we must use XDR for cross-domain requests. XDR does not support
@@ -69,7 +74,6 @@ module.exports = function (opts, callback) {
     if (opts.useCsrf) {
         jar.use('scratchcsrftoken', '/csrf_token/', function (err, csrftoken) {
             if (err) return log.error('Error while retrieving CSRF token', err);
-            opts.json.csrftoken = csrftoken;
             opts.headers['X-CSRFToken'] = csrftoken;
             apiRequest(opts);
         }.bind(this));

src/lib/url-params.js

@@ -6,7 +6,8 @@ module.exports = function urlParams (values) {
     return Object
         .keys(values)
         .map(function (key) {
-            return [key, values[key]]
+            var value = typeof values[key] === 'undefined' ? '' : values[key];
+            return [key, value]
                 .map(encodeURIComponent)
                 .join('=');
         })