added number of simulated features as a parameter.
added number of simulated features as a parameter.

ohsu-computational-biology/server,macieksmuga/server,dcolligan/server,dcolligan/server,ohsu-computational-biology/server,saupchurch/server,saupchurch/server,macieksmuga/server,david4096/ga4gh-server,ga4gh/server,dcolligan/server,david4096/ga4gh-server,saupchurch/server,macieksmuga/server,ohsu-computational-biology/server,ga4gh/server,david4096/ga4gh-server,ga4gh/server