latest code

gistfile1.txt

var uploadFile = Titanium.Filesystem.getFile(filepath, filename);
var uploadStream = Titanium.Filesystem.getFileStream(uploadFile);

uploadStream.open(Titanium.Filesystem.MODE_READ, true);
content = uploadStream.read();
uploadStream.close();
// content = Titanium.Codec.encodeBase64(content);
// content = Titanium.Codec.encodeHexBinary(content);

var name = "file";
var boundary = '----12345568790';
var header =  "--" + boundary + "\r\n";
header += "Content-Disposition: form-data; name=\"" + name + "\";";
header += "filename=\"" + filename + "\"\r\n\"";
header += "Content-Type: application/octet-stream\r\n\r\n";

var fullContent = header + content + "\r\n--" + boundary + "--";
console.log(fullContent);
xhr.addEventListener(Titanium.HTTP_DONE, function(){
    console.log("TI DONE!");
    console.log(this.responseText);
});

xhr.open('POST', api_url);
xhr.setRequestHeader('Authorization', oa.signRequest("POST", "https://api-content.dropbox.com/0/files/dropbox/JB", {file: escape(file.name)}));
xhr.setRequestHeader("Content-type", "multipart/form-data; boundary=\"" + boundary + "\"");
xhr.setRequestHeader("Connection", "close");
xhr.send(fullContent);