Beginnings of a command line tool that will email files to students.  This addresses issues #61.
More command line parsing.
Don't want that debugging statement anymore.
Pulled code for sending email into a parent class.
Refactored Survey to extend EmailSender.
Send an email to the student.  There's not body to the email, yet.
A MIME message must have a body.  Include a simple one.
Email the contents of the file.
Remove an unused field.
If none of the submissions has been graded yet, don't report the grade as "INCOMPLETE".
Merge pull request #76 from DavidWhitlock/email-file-to-students

Address issue #61 with a simple program that takes a list of files on the command line whose names correspond to student ids and emails them to the students based on their email address in the grade book.