Merge pull request #45 from Antek88/master

Remove deprecated FilterDataEvent, add validation to addressing step, small fix pl translation
Styles of buttons "Create shipping category" and "Manage shipping methods" are inverted.
Merge pull request #46 from jjanvier/master

Styles of buttons "Create shipping category" and "Manage shipping methods" are inverted.
Fix pl translation, fix payment method form
fix pl translation