Revert "try to add DB + migration"

This reverts commit 9565550f6a4806d3cd9787749adb6fda03c2e4b4.

Conflicts:
	src/main/java/ru/yandex/school/hlebushek/service/DatabaseProvider.java
Merge branch 'Sergey_hlebushek' of https://github.com/autoschool/hlebushek into Sergey_hlebushek