Added mongodb database

[ckucera3]

Added Database and Database Queries

I added a mongodb database. The URL in the code is for a database that I have running in the cloud server of https://mongolab.com. The app assumes that the database used has a collection called courses which contains documents of the following structure:

{
  "subject": "ACCT",
  "number": "2101",
  "description": "Short description.",
  "name": "Accounting I"
}

To access this data from the database, use the same queries used for the static info, with the following change to the route:

/api/db/course/...

For example, api/db/course/ACCT/2101

[stuartf]

This should probably be done as configuration either as an env variable or in a file that isn't committed. Note that there are bots that watch github for this kind of thing in order to hijack accounts.