Support more than one api key per user

[0xjei]

Description

The #318 will introduce a new kind of generic API for handling multiple groups (CRUD ops). Actually the design will support one Api Key x User. Therefore, we want to introduce a way to maintain multiple Api Keys x users to support the management of single projects (e.g. 1 apikey x 1 project), giving more freedom and security.

This may require the introduction of a profile/settings section where the user can manage the keys in an easy way. Also, only the groups created with an API key can be managed with that key (or the new one if rolled).

At implementation level, a trade-off between using an array (apikey[]) vs repeating some information ({id: 1, apikey: A}, {id: 1, apikey: B} …) must be investigated.