(WIP) Class diagram transfer

A start at transferring content from the class diagram into code.  Focuses on School/Course/Klass/Educator/Student type models.  

@Dantemss I'd appreciate a once over of this PR if you have a chance.
Can also add klasses if needed. has_many :klasses, through: :courses
You can then add students through courses or klasses, etc. Not sure how deep you need to go.