(refactor) Hid database credentials.

The credential information for the database are now stored in a local databaseCredential.js file which is ignored by git and will never be committed. The file databaseConfig.example.js shows devs how to do this on their own local machine.

When this is merged, I will reset the database credentials and each of us will have the create our own local databaseCredentials.js file locally with the info I give out. This will make our old commits safe, since we used to include the credential info.