Let the user modify some of its attributes

[coudot]

User should be able to edit some attributes, like telephone number or room number.

The list of writable attributes will be configured.

User must authenticate to edit attributes, we can propose for the moment a simple login/password in the edit attribute page.

We need an option to do the modification using the user account or using the service account.

A contribution was proposed in #105 but code quality was not as good as expected, so we need to start a new one