Improve initial load performance and Add support for Mongo Replica Sets

These proposed updated provide the following:

- Replacing the grouping request in the result listing with a single aggregate request.  Similar to what @guandalf proposed in his fork request, but instead uses a single MongoDB request with no additional indexes.

- Added support for Mongo replica sets, if desired.  This includes adding an entry in the ini files for determining if you want to use a replica set, and if so, it allows you to define the replica set name.

- Changed the MongoDB client for the cases where a replica set isn't used to remove the deprecated client.  The same thing @guandalf suggested