Update 'lang/pl.php'
Update 'lang/pl.php'

Please do not revert these changes. In Polish language in dates the name of the month must be in Genitive case.  Refer to these explanations: http://www.mediawiki.org/wiki/Template:I18n_month
http://stackoverflow.com/questions/17188316/month-name-in-genitive-polish-locale-with-joda-time-datetimeformatter
Additional note: even in Google's GMail they display the incorrect form of the months' names.
jenssegers/date,jenssegers/laravel-date