Implement models / data logic

[dianamiraflor]

Implementing the concrete classes needed for SurveyMonkey

[dianamiraflor]

March 4

Accomplished:

• Implementing the basic logic for the application
• Created classes: Survey, Surveyor, Question and classes that extend Question (MCQ, Range, Text)
• Created tests that tested basic functions, such as adding to the list of questions of a survey

I wasn't able to add the JPA annotations + docs today. But the functions are very basic

[dianamiraflor]

Added JPA annotations to the model, and used JOINED strategy for Inheritance Mapping because a single table would have empty columns for the subclasses of Questions - with the way it is currently implemented.

Let me know if you have better ways to implement inheritance between Questions and its subclasses.

[brnjamino]

updated the names and datatypes of some fields to work better with controller