Switch to driver for queries exclusively

[solnic]

It turned out origin gem has been merged into mongoid codebase and is now considered a private API. Because of this we need to rely only on the driver. If we want a fancy query DSL, we need to build it ourselves.

[estolfo]

The tests pass with these changes to remove origin and use the driver directly.

[IzumiSy]

Is there any plan to migrate to Mongoid from the current driver instead?.

[solnic]

@IzumiSy what would be the benefit of migrating to Mongoid?