jquery ajax form success callback not being called

I'm trying to upload a file using "AJAX", process data in the file and then return some of that data to the UI so I can dynamically update the screen.

I'm using the JQuery Ajax Form Plugin, jquery.form.js found at http://jquery.malsup.com/form/ for the javascript and using Django on the back end. The form is being submitted and the processing on the back end is going through without a problem, but when a response is received from the server, my Firefox browser prompts me to download/open a file of type "application/json". The file has the json content that I've been trying to send to the browser.

I don't believe this is an issue with how I'm sending the json as I have a modularized json_wrapper() function that I'm using in multiple places in this same application.

Here is what my form looks after Django templates are applied:

<form method="POST" enctype="multipart/form-data" action="/test_suites/active/upload_results/805/">
  <p>
     <label for="id_resultfile">Upload File:</label> 
     <input type="file" id="id_resultfile" name="resultfile">
  </p>  
</form>

You won't see any submit buttons because I'm calling submit with a button else where and am using ajaxSubmit() from the jquery.form.js plugin.

Here is the controlling javascript code:

function upload_results($dialog_box){
    $form = $dialog_box.find("form");
    var options = {
            type: "POST",
            success: function(data){
                alert("Hello!!");
            },
            dataType: "json",
            error: function(){
                console.log("errors");

            },
            beforeSubmit: function(formData, jqForm, options){
                    console.log(formData, jqForm, options);
                },
        }
    $form.submit(function(){
        $(this).ajaxSubmit(optio