Fix --no-paginate to check for None values

Basically --no-paginate didn't work.  If you don't check for None
values, the arg object will insert args that don't actually exist in the
op model which botocore will (correctly) complain about.

Added an integration test as well as a unit test to catch this
in the future.
Merge branch 'fix-no-paginate-arg' into develop

* fix-no-paginate-arg:
  Fix --no-paginate to check for None values