added contigs2random_sample.py
added contigs2random_sample.py

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