Don't require parseCSVResult to return a Promise

README.md

@@ -58,7 +58,7 @@ mws.Orders.ListOrders({
 Flat files:
 
 When working with a flat-file response from Amazon, a `parseCSVResult` function is provided as an
-option to conviniently post-process the result. *It must return a Promise*.
+option to conviniently post-process the result. Returning a Promise will result in the Promise being resolved.
 
 ```javascript
 // An example to change the encoding of the raw response
@@ -69,7 +69,7 @@ const mws = new MWSClient({
   secretAccessKey: 'kek',
   merchantId: 'hue',
   meta: {
-    parseCSVResult: (data) => Promise.resolve(iconv.encode(data, 'utf-8').toString())
+    parseCSVResult: (data) => iconv.encode(data, 'utf-8').toString()
   }
 });
 ```

lib/client.js

@@ -43,7 +43,7 @@ class AmazonMwsClient {
                 max_attempts: Infinity,
                 attempt: -1,
                 contentType: 'application/x-www-form-urlencoded',
-                parseCSVResult: (data) => Promise.resolve(data)
+                parseCSVResult: (data) => data
             }
         });
 
@@ -131,7 +131,8 @@ class AmazonMwsClient {
             const body = response.body;
 
             if (body.slice(0, 5) !== '<?xml') {
-                return meta.parseCSVResult(body).then((result) => ({ result, metadata: null }));
+                return Promise.resolve(meta.parseCSVResult(body))
+                    .then((result) => ({ result, metadata: null }));
             }
 
             const data = JSON.parse(parser.toJson(body));