Cloud Code: Allows user session creation with DIRECT_ACCESS

[flovilmart]

In an effort to remove the overhead of running cloud code with the HTTP interface, it's required to use the provided optional installationId.

For ex:

let user = new Parse.User();
user.save({username: "hello", password: "world"}).then((user) => {
     // the user has no Session
});

Parse.Cloud.define("signupUser", function(req, res) {
  let installationId = req.installationId; // installation Id passed by the client
  let user = new Parse.User();
  user.save({username: req.username, password: req.pass}, { installationId }).then((user) => {
    // the session token will be valid for that user!
    res.success(user.getSessionToken());
  });
});

[facebook-github-bot]

@flovilmart updated the pull request - view changes