Fix body params format

Hi, I encountered #240 issue and fix it.
fix https://github.com/knuckleswtf/scribe/issues/240

```
    if (form.dataset.hasfiles === "0") {
        body = {};
        setter = (name, value) => _.set(body, name, value);
    } else {
        body = new FormData();
        setter = (name, value) => body.append(name, value);
    }
```

resources/views/themes/default/endpoint.blade.php

@@ -63,7 +63,7 @@
 <form id="form-{{ $endpoint->endpointId() }}" data-method="{{ $endpoint->httpMethods[0] }}"
       data-path="{{ $endpoint->uri }}"
       data-authed="{{ $endpoint->metadata->authenticated ? 1 : 0 }}"
-      data-hasfiles="{{ $endpoint->hasFiles() }}"
+      data-hasfiles="{{ $endpoint->hasFiles() ? 1 : 0 }}"
       data-headers='@json($endpoint->headers)'
       onsubmit="event.preventDefault(); executeTryOut('{{ $endpoint->endpointId() }}', this);">
     <h3>