resolves #16, separated OTP into behavior, refactored forms to extract duplicated code into base classes and behaviors; resolves #21 and resolves #20, implemented password history table, model and validation; minor improvements; updated polish translation; moved password strength rules as module option so it's configurable; refactored all example migrations and models to use plural table names; extracted password fields from ProfileForm into PasswordForm
Merge branch 'master' of git://github.com/nineinchnick/yii-usr

Conflicts:
	migrations/m130702_104658_create_table_user_remote_identity.php