bam2peakshape.py - added warning message for empty input
bam2peakshape.py - added warning message for empty input

AntonioJBT/CGATPipeline_core,AntonioJBT/CGATPipeline_core,CGATOxford/CGATPipelines,CGATOxford/CGATPipelines,CGATOxford/CGATPipelines,CGATOxford/CGATPipelines,AntonioJBT/CGATPipeline_core,AntonioJBT/CGATPipeline_core,CGATOxford/CGATPipelines