Fix for #65

[wingedfox]

Added "Content-Type" header

Example of server-side response for preflight cors request

response.setHeader("Access-Control-Allow-Origin", "*"); if ("options".equals(req.getMethod().toLowerCase())){response.addHeader("Access-Control-Request-Method", "POST"); response.addHeader("Access-Control-Allow-Headers", "Content-Range, X-Requested-With, Content-Disposition, Content-Type"); returnnull}