By Denny Dyroff, Entertainment Editor, The Times Heather Gillis Kennett Flash will be rocking this Friday night. Heather Gillis, a Nashville-based blues rocker from Florida, will make her Chester County debut on July 12 at Kennett Flash (102 Sycamore Alley, Kennett Square, 484-732-8295, http://www.kennettflash.org). Gillis is primarily a guitarist/vocalist but is much more than that. She is an...