Check permissions method doesn't handle pagination properly

[sambhav]

permissions endpoint returns a paginated list. The current get_permissions method does not account for it.

kinto-http.py/src/kinto_http/client.py

Line 682 in 1182c29

def get_permissions(self, exclude_resource_names=None, **kwargs):

It should use pagination properly. This is handled appropriately in https://github.com/Kinto/kinto.js/blob/9e8086989a59beaa9616c6cd8aaa1d756cda66f4/src/http/base.ts#L849