Feature/significant upload email alerts

This change sets requires: 

1.  Running db:migrate 

2.  Creating a config/application.yml file that defines the constants used to configure the Mailer.  I'll send an email around with what I have; I made a gmail account for the express purpose of testing.  

3.  Running `bundle exec whenever --update-crontab` from project root will update your cron table.  The role particular designation on the one job we have should mean that nothing actually gets added, I think.  

The code that handles taking a file upload, determining if it is 'significant content' and adding an UploadEntry to the SQL table is not implemented by this pull request.  This is the case because it is easy code that would potentially need to be rewritten once we'd moved to a single file upload process.  Once single file upload is on develop I can write it.  

We'll also want to clean up who the email is being sent to/where the email is being sent from once we're ready to roll this out to production.