<issue_start><issue_comment>Title: Request.user undefined and no information in request 
username_0: I'm trying to access a user in cloud code so I can modify user data. I don't have access to any session tokens and request.user is undefined
### Steps to reproduce

Swift: 

 PFCloud.callFunctionInBackground("checkUser", withParameters: nil) {
            (response: AnyObject?, error: NSError?) -> Void in
            let responseString = response as? String
            print(responseString)
        }

Main.js

Parse.Cloud.define("checkUser", function(request, response) {
    console.log(request);
    var user = request.user;
    response.success(user);
});
#### Expected Results

request.user or request.user.getSessionToken() give me correct data 
#### Actual Outcome

request.user is undefined 
### Environment Setup
- **Server**
  - parse-server version: latest
  - Operating System:     OS X El Capitan
  - Hardware:            Macbook pro
  - Localhost or remote server? (AWS, Heroku, Azure, Digital Ocean, etc): Locally and AWS Beanstalk
- **Database**
  - MongoDB version: latest
  - Storage engine:  mLabs
  - Localhost or remote server? (AWS, mLab, ObjectRocket, Digital Ocean, etc): [FILL THIS OUT]
### Logs/Trace

[31merror[39m: Uncaught internal server error. [TypeError: request.user is not a function] TypeError: request.user is not a function
    at /var/app/current/cloud/main.js:54:24
    at /var/app/current/node_modules/parse-server/lib/Routers/FunctionsRouter.js:95:11
    at new Promise (/var/app/current/node_modules/parse-server/node_modules/babel-polyfill/node_modules/core-js/modules/es6.promise.js:193:7)
    at handleCloudFunction (/var/app/current/node_modules/parse-server/lib/Routers/FunctionsRouter.js:89:16)
    at /var/app/current/node_modules/parse-server/lib/PromiseRouter.js:286:7
    at Layer.handle [as handle_request](/var/app/current/node_modules/parse-server/node_modules/express/lib/router/layer.js:95:5)
    at next (/var/app/current/node_modules/parse-server/node_modules/express/lib/router/route.js:131:13)
    at Route.dispatch (/var/app/current/node_modules/parse-server/node_modules/express/lib/router/route.js:112:3)
    at Layer.handle [as handle_request](/var/app/current/node_modules/parse-server/node_modules/express/lib/router/layer.js:95:5)
    at /var/app/current/node_modules/parse-server/node_modules/express/lib/router/index.js:277:22

I passed the session token myself, but this doesn't seem secure 

{ params: { sessionToken: 'XXXXXXXXXXXXXXXXXX' },
  master: false,
  user: undefined,
  installationId: 'xxx-xxx-xxx-xxx',
  log: FileLoggerAdapter {} }