The daemon already pings the registry, so doing it on our end is
redundant and error-prone.

The `insecure_registry` argument to `push()`, `pull()` and `login()` has
been deprecated - in the latter case, it wasn't being used anyway.

The `insecure` argument to `docker.auth.resolve_repository_name()` has
also been deprecated.

`docker.utils.ping_registry()` has been deprecated.

`docker.auth.expand_registry_url()` has been removed.
Signed-off-by: Aanand Prasad <aanand.prasad@gmail.com>