In case its useful Im using the chrome Postman rest client to send the request. Here is the Curl of what im sending (with username and password hidden of course)
curl -X POST -H "Cache-Control: no-cache" -H "Postman-Token: cd67a1bb-5e20-b738-0e76-67ccec54f4c4" -H "Content-Type: multipart/form-data; boundary=----WebKitFormBoundaryp7MA4YWxkTrZu0gW" -F "userName=xxxxx" -F "password=xxxxxxx" https://api2.clarizen.com/v1.0/services/authentication/login