add ability to filter by value using query params

closes https://gitlab.coko.foundation/pubsweet/pubsweet-server/issues/53

Query parameters can be provided as either object properties or paths:

GET /collections?type=foo
GET /teams?object.id=434242342342

If a query parameter is provided for which there is no authorization or no match on the object the result is an empty array.

This is crude but hopefully suffices. Since we were already summoning objects from the db en masse without pagination I assume that implementing proper db queries is not part of this requirement (and certainly seems like overkill for 1.0).