added some tests for user

core/pom.xml

.../src/main/java/cz/muni/fi/pa165/core/CoreApplication.java

.../src/main/java/cz/muni/fi/pa165/core/DataInitializer.java

.../main/java/cz/muni/fi/pa165/core/common/DomainFacade.java

...main/java/cz/muni/fi/pa165/core/common/DomainService.java

...java/cz/muni/fi/pa165/core/company/CompanyRepository.java

...in/java/cz/muni/fi/pa165/core/company/CompanyService.java

...a165/core/helpers/exceptions/EntityConflictException.java

core/src/main/java/cz/muni/fi/pa165/core/user/User.java

.../main/java/cz/muni/fi/pa165/core/user/UserController.java

.../src/main/java/cz/muni/fi/pa165/core/user/UserFacade.java

.../main/java/cz/muni/fi/pa165/core/user/UserRepository.java

...src/main/java/cz/muni/fi/pa165/core/user/UserService.java

core/src/main/resources/application.properties

.../test/java/cz/muni/fi/pa165/core/CoreApplicationTest.java

core/src/test/java/cz/muni/fi/pa165/core/Persistence.java

.../cz/muni/fi/pa165/core/company/CompanyControllerTest.java

...t/java/cz/muni/fi/pa165/core/user/UserControllerTest.java

core/src/test/resources/META-INF/persistence.xml

core/src/test/resources/application-test.properties