Update pl.po

This is complete renewal of polish translation. It's not perfect, but it makes openATV image usable for users without English language knowledge. Current translation is far obsolete causing several confusions on user side. This is milestone for openATV image promotion among polish Enigma2 based SAT receivers.
Merge pull request #108 from simon-ttp/master

Major renewal of pl.po - openATV promotion among polish Enigma2 users