fixing tests for usage of JPA

currency-service/pom.xml

...rvice/src/main/java/cz/muni/fi/obs/data/dbo/Currency.java

...e/src/main/java/cz/muni/fi/obs/data/dbo/ExchangeRate.java

.../cz/muni/fi/obs/data/provider/RepositoryDataProvider.java

.../muni/fi/obs/service/update/NbsCurrencyUpdateService.java

...ncy-service/src/test/java/cz/muni/fi/obs/Application.java

...c/test/java/cz/muni/fi/obs/facade/CurrencyFacadeTest.java

...ava/cz/muni/fi/obs/repository/CurrencyRepositoryTest.java

...test/java/cz/muni/fi/obs/service/CurrencyServiceTest.java

.../java/cz/muni/fi/obs/service/ExchangeRateServiceTest.java

currency-service/src/test/resources/application.yml