added email.go to handle everything we have to do with emails. can send emails to students after class creation. added a few comments to the tops of files (just to help figure out what each file is doing without having to scroll down the whole thing all the time)
DO NOT MERGE WIP, committing local changes from working on add student and sending email
DONE - creates hash for each student and sends email
Merge pull request #37 from michellefish/master

generate random ID for each class student, email it to them