Description of problem:
As per #1324508, `organization_ids` and `location_ids` are accepted for Discovery rule's POST and PUT requests, however this requests do not return these parameters and their values.

Version-Release number of selected component (if applicable):
Sat 6.3.0 Snap 4

How reproducible:
Always

Steps to Reproduce:
1. Issue HTTP POST request to /api/v2/discovery_rules. Example of request body: {"discovery_rule": {"organization_ids": [15], "name": "test", "search": "cpu_count > 3", "hostgroup_id": 1, "location_ids": [42]}}
2. Issue HTTP PUT request to /api/v2/discovery_rules/:id. Example of request body: {"discovery_rule": {"organization_ids": [16], "location_ids": [43]}}
3.

Actual results:
`organization_ids` and `location_ids` are accepted but never returned.
Example of output:
{
"id": 3
"name": "test4"
"search": "cpu_count > 3"
"hostgroup_id": 1
"hostname": ""
"max_count": 0
"priority": 0
"enabled": true
"created_at": "2016-10-21T12:47:36.244+03:00"
"updated_at": "2016-10-21T12:47:36.244+03:00"
}

Expected results:
List of associated organizations and locations should be returned altogether with the rest parameters, preferably in the same way as we have for GET request:
{
[...]
"locations":[{"id":42,"name":"scsdfdfsd","title":"scsdfdfsd","description":""}],
"organizations":[{"id":15,"name":"3J89gV","title":"3J89gV","description":null}]
}

Additional info:
Low-priority issue as we can still get the list of associated organizations and locations by issuing GET request.