$http.post Request header field Access-Control-Allow-Origin is not allowed by Access-Control-Allow-Headers error

I'm working on a app using Ionic Framework.

On the backhand i wrote a Flask Application for api which looks like below:

@API.route("/saverez",methods=["POST","OPTIONS"])
@crossdomain(origin='*', headers="*",methods="*")   
@render_api
def saver():
 .....

I got errors while posting json to api.

var headers = {
                    'Access-Control-Allow-Origin' : '*',
                    'Access-Control-Allow-Methods' : 'POST, GET, OPTIONS',
                    'Accept': 'application/json'
                };

                $http({
                    method: "POST",
                    headers: headers,
                    url: url+ '/api/saverez',
                    data: $scope.form
                }).success(function (result) 
                    console.log(result);
                }).error(function (data, status, headers, config) {
                    console.log(data);
                    console.log(status);
                    console.log(headers);
                    console.log(config);
                });

So this gives me the error:

XMLHttpRequest cannot load http://myurl/api/saverez. Request header field Access-Control-Allow-Origin is not allowed by Access-Control-Allow-Headers. 

I googled it and then i found this snippet:

http://flask.pocoo.org/snippets/56/

I also added headers to my nginx conf like below:

location ~* \.(eot|ttf|woff)$ {
    add_header Access-Control-Allow-Origin *;
}

Tried everything in that documentation and also evertyhing i found on google but sadly it didn't do any good.

How can i set the right headers for all origins ? I also use google pagespeed does it can cause this issue ?

Thanks in advance.

--- EDIT --- Chrome network output

Remote Address:myip
Request URL:http://myurl/api/saverez
Request Method:OPTIONS
Status Code:200 OK
Request Headersview source
Accept:*/*
Accept-Encoding:gzip,deflate,sdch
Accept-Language:en-US,en;q=0.8
Access-Control-Request-Headers:access-control-allow-origin, accept, access-control-allow-methods,          content-type
Access-Control-Request-Method:POST
Cache-Control:no-cache
Connection:keep-alive
Host:myurl
Origin:http://192.168.1.46:8100
Pragma:no-cache
Referer:http://192.168.1.46:8100/
User-Agent:Mozilla/5.0 (iPhone; CPU iPhone OS 7_0 like Mac OS X; en-us) AppleWebKit/537.51.1 (KHTML,     like Gecko) Version/7.0 Mobile/11A465 Safari/9537.53
Response Headersview source
Access-Control-Allow-Credentials:true
Access-Control-Allow-Headers:*
Access-Control-Allow-Methods:*
Access-Control-Allow-Origin:*
Access-Control-Max-Age:21600
Allow:POST, OPTIONS
Content-Length:0
Content-Type:text/html; charset=utf-8
Date:Thu, 28 Aug 2014 13:26:11 GMT
Server:nginx/1.6.0