Created interface to communicate with DB

* implemented logIn and logOut Methods but they are not working yet
* added sql script to create db
* use this link as a tutorial to create a user and grant him access to
the DB https://help.ubuntu.com/community/JDBCAndMySQL
* USERNAME: coffee, PASSWORD: coffee

Signed-off-by: Martinas Mihaela <martinas.mihaela21@gmail.com>