JIRA INFRA-931 #action In Progress

- add fqdn to host
- add gateway to network
- add netmask to interface
- allow to pass recursive via the API (to expand interfaces in host)
- add is_main property to interface (True if the interface is the main
  interface of the host)

JIRA INFRA-640

Add endpoints:
DELETE /network/hosts/<host_id>
DELETE /network/interfaces/<interface_id>

JIRA INFRA-570 #action In Progress

https://black.readthedocs.io/en/stable/

Pagination information (next, prev, first, last) is included in the Link
HTTP header.
The total number of entries is provided in the X-Total-Count HTTP
header.

+ fix tests

Split API in different blueprints like for the web UI:
- users (login)
- inventory
- network

Use version in API url (api/v1) to make future changes easier without
breaking backward compatibility