dodana obsluga sesji.
male poprawki
dodane kolumny do modeli
Merge pull request #2 from rusinekm/michal

Michal
First test for Car model
test for blank in Car + helper method
validation for brand presence
Test for blak properties + validations
Tests and validations for integer in mileage, production_year
Merge pull request #4 from rusinekm/adam

Adam
marcin
marcin_poprawa_widoku_dla_kontrolera_admin
widoki_dla_usera