Description of problem:

I previously used the rest-api endpoint "/katello/api/v2/environments" with sort_by=id. It works with 6.4 and 6.3.
 
After the upgrade to 6.5 i noticed i was not getting the lifecycle environmens list. After some diagnosis i noticed that the endpoint changed behaviour.

I use the endpoint in a ruby script that i wrote, but i put regular CURLs on the bugreport.

Was "sort_by=id" removed?

Version-Release number of selected component (if applicable):
6.5.0

How reproducible:
always

Steps to Reproduce:
This used to work for Sat 6.4 and 6.3, it does not work with Sat 6.5
$ curl -k -u admin:redhat01 -X GET https://sixthsat2.example.com/katello/api/v2/environments?page=1\&sort_by=id\&per_page=10\&sort_order=ASC
{"total":0,"subtotal":0,"page":null,"per_page":null,"error":"the field 'id' in the order statement is not valid field for search","search":null,"sort":{"by":"id","order":"ASC"},"results":[]}

Actual results:
This used to work for Sat 6.4 and 6.3, it does not work with Sat 6.5
$ curl -k -u admin:redhat01 -X GET https://sixthsat2.example.com/katello/api/v2/environments?page=1\&sort_by=id\&per_page=10\&sort_order=ASC
{"total":0,"subtotal":0,"page":null,"per_page":null,"error":"the field 'id' in the order statement is not valid field for search","search":null,"sort":{"by":"id","order":"ASC"},"results":[]}

Expected results:

Workarounds:
a) remove sorting:
$ curl -k -u admin:redhat01 -X GET https://sixthsat2.example.com/katello/api/v2/environments?page=1\&per_page=10\&sort_order=ASC
b) sory by name instead. (But sorting by name does work. I no longer have a Sat 6.4 to test ATM.)
$ curl -k -u admin:redhat01 -X GET https://sixthsat2.example.com/katello/api/v2/environments?page=1\&sort_by=name\&per_page=10\&sort_order=ASC

Additional info:
I re-checked the apidoc but i found no help on "valid" sort_by values. So i cannot know if this is intentional or just a bug.
On the APIDOC:
 sort_by -> optional "Field to sort the results on"
 Validations: String
And no more info.