(+) service DAO covering API methods; DB integration and unit tests for user
(+) link posting ligic added; tests written
(+) click stats posting and link retrieval logic added (tests covered)
(+) getting stats for link code logic added
(+) get folder links logic added
(+) get user links logic added
(+) folders list logic added; (~) minor tests refactoring
(+) clicks request logic added
(+) folder creation logic added