Feature: Data from MongoDB

_From @tandasima on December 4, 2014 2:7_

Thanks for this awesome plugin. I think adding MongoDB database to the available data sources that work with this plugin would be great :)

Thanks,
Sunday

_Copied from original issue: no81no/jplist#49_

The issue requests adding MongoDB as a data source to the jPList plugin. First, examine the existing data source implementations in the codebase to understand the interface. Look for database connection logic and how data is fetched and formatted for jPList. Determine what 'done' looks like by checking if there are tests for other data sources and see if MongoDB queries need to be integrated similarly.

索引モデルが issue の本文から書いたものです。