HTTP Error 400 is thrown when trying to upload a Logo in the Admin Area

[chunyianliew]

When I try to upload a new logo in the admin area, an HTTP 400 Error is returned.
I managed to reproduce the error on the live preview/demo site: http://demo.estatezilla.com/

Steps to reproduce:
Open http://demo.estatezilla.com/admin
Login as 'admin'
Click on the cogwheel top right just left of the logout button, this will open http://demo.estatezilla.com/admin/#/app/settings/index
The Settings Page is shown and the General tab is selected.
In the top area 'Website Information' try to upload an image file via the file upload field.
The logo is not successfully uploaded and the error is thrown (visible when using Chrome, View -> Developer -> Javascript Console)

The following information is shown in the Javascript Console of Chrome

Headers:
Request URL:http://demo.estatezilla.com/admin/api/settings/upload
Request Method:POST
Status Code:400 Bad Request

Response:
{"error":"invalid_request","error_description":"The request is missing a required parameter, includes an invalid parameter value, includes a parameter more than once, or is otherwise malformed. Check the "access token" parameter."}