postFile method
Implementation
Future<http.Response> postFile(String path, String filePath) {
var uri = Uri(scheme: _scheme, host: _server, port: port, path: path);
var request = http.MultipartRequest('POST', uri);
return http.MultipartFile.fromPath('file', filePath).then((value) {
request.files.add(value);
request.headers.addAll(getHeaders());
return request.send().then((value) => http.Response.fromStream(value));
});
}