add first and last handling

[alexpantyukhin]

No description provided.

[abawchen]

@alexpantyukhin 👍

It turns out that I make things complicated :<
The errors raised just because first/last can't be passed into filter: objs = objs.filter(**args) -- maybe:

objs = model.objects()

if args:
    first = args.pop('first', None)
    last = args.pop('last', None)
    objs = objs.filter(**args)

    if first is not None:
        objs = objs[:first]
    if last is not None:
        objs = objs[:-last]

return objs       

but it's untidy. Any thought?

[alexpantyukhin]

@abawchen Yes! I think you are right about excluding first and args from params.
For my view: maybe for the first it's would be untidy, but it's clear for reading.
For TODO there could be some filter of params which filters only fields which are in the Model.
What do you think about it?