Merge pull request #15 from dcs24/master

Basic Data Objects and QuestionServiceInterface. Reviewed design, style, algorithms, security, error checking.
Added PaginatedResults object and Jackson JSON library
code review changes
Merge pull request #16 from bkng/master

Added PaginatedResults object and Jackson JSON library
updated UML class diagram with PaginatedResults class
Reorganized packages. Added LikeableObject interface.
code review change
Merge pull request #26 from bkng/master

Reorganized packages and added LikeableObject interface.
Added getFavorites method to QuestionServiceInterface. Added equals and hashcode functions to Question and Solution classes.