Fix - close mongo connection after import

Howdy,

We ran into an issue where our mongo started refusing connections from solr because there were too many open concurrent connections. This is because the module never closes the mongo connection after completing an import.

We also need to make changes to it to support Mongo replica sets and had to upgrade the mongo driver version to do so, but the closing of the mongo connection after import is the important patch.

cheers,
Boris.