By Denny Dyroff, Entertainment Editor, The Times We Were Promised Jetpacks We Were Promised Jetpacks, which is headlining a show on April 14 at Underground Arts (1200 Callowhill Street, Philadelphia, http://undergroundarts.org), is a Scottish indie rock band featuring Adam Thompson (vocals, guitar), Sean Smith (bass), and Darren Lackie (drums). “The band started back in 2004 when we were in school,”...