Merge branch 'dev' into 'airplane'

# Conflicts:
#   .gitignore
#   core/src/main/java/cz/muni/fi/pa165/core/dto/AirplaneDto.java
#   core/src/main/java/cz/muni/fi/pa165/core/dto/DestinationDto.java
#   core/src/main/java/cz/muni/fi/pa165/core/dto/FlightDto.java
#   core/src/main/java/cz/muni/fi/pa165/core/dto/StaffDto.java
#   modules/airplane/pom.xml
#   modules/airplane/src/main/java/cz/muni/fi/pa165/airplane/service/AirplaneController.java
#   modules/airplane/src/main/java/cz/muni/fi/pa165/airplane/service/AirplaneService.java
#   modules/destination/pom.xml
#   modules/destination/src/main/java/cz/muni/fi/pa165/destination/service/DestinationController.java
#   modules/destination/src/main/java/cz/muni/fi/pa165/destination/service/DestinationService.java
#   modules/staff/pom.xml
#   modules/staff/src/main/java/cz/muni/fi/pa165/staff/service/StaffController.java
#   modules/staff/src/main/java/cz/muni/fi/pa165/staff/service/StaffService.java