BURUNDI on Friday briefly detained a journalist investigating a grenade attack in the commercial capital Bujumbura, his radio station and an official said, after a series of explosions this week that killed at least five people. Radio Bonesha FM said their reporter was arrested while investigating a grenade incident that was said to have killed two people on Thursday. "Radio Bonesha FM journalist arrested on Friday morning by the police has just been released. Aimé Richard Niyonkuru is still waiting for his recorder. He spent many hours at the Special Research Office under the hot sun," the station wrote on…