added a function to compute a distribution object from phenotype associations
added a function to compute a distribution object from phenotype associations

kshefchek/monarch-app,kshefchek/monarch-app,monarch-initiative/monarch-app,DoctorBud/monarch-app,monarch-initiative/monarch-app,DoctorBud/monarch-app,jmcmurry/monarch-app,DoctorBud/monarch-app,jmcmurry/monarch-app,jmcmurry/monarch-app,kshefchek/monarch-app,jmcmurry/monarch-app,kshefchek/monarch-app,monarch-initiative/monarch-app,DoctorBud/monarch-app,jmcmurry/monarch-app,monarch-initiative/monarch-app,kshefchek/monarch-app,monarch-initiative/monarch-app,DoctorBud/monarch-app