Change flat_map to map.flatten to support earlier versions of Ruby 1.9
Change flat_map to map.flatten to support earlier versions of Ruby 1.9

Signed-off-by: David Celis <aa743a0aaec8f7d7a1f01442503957f4d7a2d634@davidcelis.com>

davidcelis/recommendable,AndyObtiva/recommendable,balmbees/recommendable,mikesmayer/recommendable