Have pager return Nones if the server returns null.
Have pager return Nones if the server returns null.

This temporarily resolves an issue where the TheMovieDb server returns
nulls in searches when a movie has been deleted but not yet flushed out
of the cache. This prevents the error internally, but does not attempt
to re-order to remove the nulls, so is merely passing the issue onto the
application using this library.

Refs #29

wagnerrp/pytmdb3,naveenvhegde/pytmdb3