re #44 add DB migration engine
re #29 backend implementation of Google OAuth2 authentication
Includes new user registration.
re #37 add spring security to dependencies
re #30: rename base package and groupId
re #28 proper Dockerfile for server build, related pom.xml changes
Fixed JUnit test via Maven
Re #7530 Get 'vacation' and 'overtime' from input xlsx file
Re #7491 Implemented API for import/export with mocked PDF and XLS processing
Re #7477 Edited endpoints and created mock manager for data
Fixing directory structure
Re #7386 Implemented APIs endpoints with DTOs