Merge branch 'dev' into 'airplane'

# Conflicts:
#   modules/airplane/pom.xml
#   modules/airplane/src/main/java/cz/muni/fi/pa165/airplane/data/Airplane.java
#   modules/airplane/src/main/java/cz/muni/fi/pa165/airplane/data/AirplaneRepository.java
#   modules/airplane/src/main/java/cz/muni/fi/pa165/airplane/service/AirplaneController.java
#   modules/airplane/src/main/java/cz/muni/fi/pa165/airplane/service/AirplaneFacade.java
#   modules/airplane/src/main/java/cz/muni/fi/pa165/airplane/service/AirplaneService.java