Replaced LocalDateTime with Instance

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

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

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

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

...main/java/cz/muni/fi/pa165/core/device/DeviceService.java

...a/cz/muni/fi/pa165/core/smartmeter/SmartMeterService.java

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

...ava/cz/muni/fi/pa165/core/company/CompanyServiceTest.java

.../java/cz/muni/fi/pa165/core/device/DeviceServiceTest.java

.../java/cz/muni/fi/pa165/core/device/UnitTestDeviceJPA.java

...ava/cz/muni/fi/pa165/core/metrics/MetricsServiceTest.java

.../muni/fi/pa165/core/smartmeter/SmartMeterServiceTest.java

...test/java/cz/muni/fi/pa165/core/user/UserServiceTest.java

...muni/fi/pa165/core/user/roles/CompanyRoleServiceTest.java

...z/muni/fi/pa165/core/user/roles/HouseRoleServiceTest.java