Documentation of the transformData parameter

Let's face it, transformData might just be the worst name possible since transform is a very vague verb and data is almost everything in software.

I'm considering convertKeys but suggestions are welcome 😄

Of course the old transformData should be kept working (with

It would be nice to somehow register the default fields that should be on response for each resource.
This would avoid repetitive includes and decrease the payload.

Description

Fix code duplication detected by code climate on the back end repository. (https://codeclimate.com/github/fga-gpp-mds/Falko-2017.2-BackEnd/issues?category=duplication&engine_name%5B%5D=structure&engine_name%5B%5D=duplication)

Expected behavior

Don't have any duplication.

Current behavior

Has code duplication.

Checklist

• This issue has a significant name.

When we create and update a user, we currently pass in roles one at a time, and you must edit a user multiple times to add multiple roles. Thus, we want to give ourselves the ability to add more than one at the time. This is paired with another issue in the CMS, as we will need to update the form for the creation/update of users.