Add Hibernate DAO implementations
Refactor all instances of variables 'fs' and '**airport' to 'flightStatsId' and '**AirportIataCode'
Standarize names of controllers and services to singular. Rename variables with confuse meanings
Extract logic related to schedules into a separate Service class
Create a base class for persistable entities, containing creation date field and getter/setter
Refactor DAOs to a common DAO generic interface with two abstract implementations for JDBC and Hibernate