Friday Evenings: Slack Key Guitar Concerts.  Traditional Hawaiian slack key guitar and `ukulele concerts. May 6 – Tour of the Islands; May 13 – Hawaiian Slack Key; May 20 – Honoring Raymond Kane; May 27 – `Ohana Slack Key.  Free gift drawing.  Tickets: $20 ($15 keiki/seniors).  Slack key guitar and `ukulele in the real old style.  All traditional music with songs and stories of the islands, telling the history of this Hawaiian musical art form.  Voted 2014 Best Live Show in…