Adding Support For Chunk File Upload

Changes to implement chunk file upload, more information on the README

README.md

@@ -67,6 +67,11 @@ Easy to use Angular2 directives for files upload ([demo](http://valor-software.g
   5. `formatDataFunction` - Function to modify the request body. 'DisableMultipart' must be 'true' for this function to be called.
   6. `formatDataFunctionIsAsync` - Informs if the function sent in 'formatDataFunction' is asynchronous. Defaults to false.
   7. `parametersBeforeFiles` - States if additional parameters should be appended before or after the file. Defaults to false.
+  8. `chunkSize` - The Size of each chunk in Bytes, if this parameter is set the file chunk upload functionality will run. Defaults to Null.
+  9. `currentChunkParam` - Parameter Sent with the chunk request, the current chunk number of the file. Defaults to 'current_chunk'.
+  10. `totalChunkParam` - Parameter Sent with the chunk request, the total number of chunks of the file. Defaults to 'total_chunks'.
+  11. `chunkMethod` - After the first chunk, this method is set. Defaults to 'PUT' because is the standard for update.
+  
 
 ### Events
 
@@ -84,6 +89,20 @@ Please follow this guidelines when reporting bugs and feature requests:
 
 Thanks for understanding!
 
+### Using/Sending Chunk Files Feature
+  
+  If you want to send the files chunked you can just set the chunk paramets on the uploader object
+
+  If your chunk request changes the link after the first request you should use this code
+  ```
+  this.uploader.onCompleteChunk = (item,response,status,headers)=>{
+        response = JSON.parse(response);
+        if(response['id']){
+            item.url = YOUR_NEW_URL+response['id']+'/';
+        }
+    }
+  ```txt
+
 ### License
 
 The MIT License (see the [LICENSE](https://github.com/valor-software/ng2-file-upload/blob/master/LICENSE) file for the full text)