Follow principles of good REST design in API

[mvsjober]

https://codeplanet.io/principles-good-restful-api-design/

For example use POST for adding new item, and PUT for updating existing one. Right now POST are used for both.

Standardise to plural form for endpoints. E.g. POST /profiles, GET /profiles/{id}

[mvsjober]

For the new Profile API I have tried to follow these. Updating the other APIs will break compatibility unless we implement a versioning mechanism.

[mvsjober]

One option is to put the refactored API under e.g. /api/v2 or similar, and keep the old one at /api for some time.