BLACK COUNTRY COMMUNION    Luminaries from the rock world find their own chemistry together   Black Country Communion’s latest record, Afterglow, wasn’t even out when reports began flying that tension between singer and bassist Glenn Hughes and guitarist Joe Bonamassa could mean the end of the hard-rock supergroup. But in no time the dustup was quelled. “We’re really good friends,” Hughes says. “It was just a small blip there for...