Gretchen Kelly is a well-known face in Dayton night life.  If you enjoy delicious OE pizza, heading out for occasional drinks, or local music, chances are you've run into Gretchen out there in our city.  She talks with me on this episode about her new business venture, Mercenary Bartenders.  What kind of niche are they filling in our community?  What's Gretchen's favorite Dayton band?  What was the first music she can remember hearing?  What in the world is liquor liability insurance?  You'll learn…