added Vote model to facilitate many-to-many relationship between email and user
* added activerecord associations
* new emails are created with specially-flagged Vote objects to indicate the creating user
allow editing, updating, destroying emails only by admin or creator of email
hide inappropriate actions from users regarding emails they didn't create
simple upvote toggle system
Merge pull request #1 from nelsonblaha/master

Stuff I did in Digital Enterprise Management class while prof explained Google to us