Motor get_database method kwargs support

[Olegt0rr]

Motor supports additional options for databases

def get_database(self, name=None, codec_options=None, read_preference=None,
                     write_concern=None, read_concern=None):
    ...

I always use feature with setting read_preference=ReadPreference.SECONDARY_PREFERRED.
It's really helps with highload apps.

Why don't you pass this options to AIOEngine init?

[art049]

Thanks, yes support of additional preferences was totally planned. It should be included as well in the find/save method as well but setting it globally on the engine first is totally ok to me !

[robert-nash]

This looks really useful for me to read all dates as UTC dates. I wondered if there is another solution which has made this PR redundant or if there is anything I can do to help move this forward?