Allow to perfrom search of words entered with Cyrillic letters(probably will work with other national alphabets too).
Checked with Kodi 2:14.0~git20141208.0500-c489922-0trusty/plugin.video.bromix.youtube.alpha28

The Cyrilic string passed to plugin as str containing utf-8 and stored in search history as unicode utf-8. Added branching
to process str/unicode differently and avoid exception on ascii conversion of str containing utf-8