Fixes #13775 - merge if data set is present

Fixes #17678 - APIdoc - URL desc add missing CR types

Fixes #17525 - Add a friendly error message to invalid dns_id

refs #17257 - remove interpolation from extracted string

Fixes #17257 - Allow specific configs to be recreated

Fixes #17503 - Only trigger PXELoader suggestion when needed

Previously every host instantiation triggered a PXELoader suggestion,
which led to up to 3 extra queries per host loaded. This changes so that
the suggestion is only applied when a host changes it's OS.

Fixes #17487 - support sessions for api calls

- authenticated api calls save user to session and set
flag api_authenticated_session
- sessions with such flag allow posting requests without CSRF token
- api sessions exipre the same way as UI sessions
- api sessions don't store any additional data to keep the requests...

Fixes #16422 - Foreman API throws ruby exception with ovirt network API

Passing a 'nil' resource_class to the `scope_for` method will always result in a 500 as you cannot call `.where` on nil.

Fixes #17483 - async task creation returns 202

Includes task link in response

Fixes #15779 - make background processing available