Re-use Mongo connections better
Re-use Mongo connections better

It turns out that every time you call MongoClient.GetDatabase(), it
opens a new connection for that query. So cache the database objects
returned by the Mongo driver, and re-use them.

sillsdev/LfMerge,ermshiperete/LfMerge,ermshiperete/LfMerge,ermshiperete/LfMerge,sillsdev/LfMerge,sillsdev/LfMerge