REST API: for user endpoint return selected values and remove password

[waychal]

In REST API, for user endpoint return selected values like first_name, last_name, id, date_joined, email, institution, etc. and remove password

[waychal]

All endpoints of the user will be removed for security reasons.
In api.py user endpoints are commented and code is not completely removed. Resource and translator class is still there but not used.

[waychal]

merged pull request successfully

[waychal]

Remove user documentation

[ltalirz]

@waychal I'm reading through the documentation of the restapi and I'm starting to wonder:
Does it really make sense to remove the users endpoint completely?
The list of users is something one could anyhow get from the database in other ways I guess (unless we want to completely hide any information about the users).
Completely hiding user information is not practical, it is an important part of the provenance and we reference the user ids in different places (e.g. the groups endpoint).

The main security concern was that the password field (although currently unused) was shown.
Why not simply hide the password field (and, in materialscloud, also anything related to authentication)?

[sphuber]

Fixed in PR #878