Post AJAX JSON with session id
I am using POSTMAN to test my REST calls to server. 

When i try http://mysite.com/api/endpoint/users/login.json

with parametes 


Content-Type - application/json
username - A valid username on site
password - users password 


I get a json looks like this 

{
    "sessid": "6nRaPdlYfV4mDt0cgUHfGwNmWJZNvUfKM618DYY4unc",
    "session_name": "SESS4356595e5cb4b5df8f18058cfbd8d13a",
    "user": {
        "uid": "144",


From that i suspect you should pass sessid and session_name to get it work. 

Try it and let me know whether its working if not we find some other solution which works :)