allow mixpanel to be disabled for unit tests
allow mixpanel to be disabled for unit tests

total-impact/total-impact-core,total-impact/total-impact-core,Impactstory/total-impact-core,Impactstory/total-impact-core,total-impact/total-impact-core,total-impact/total-impact-core,Impactstory/total-impact-core,Impactstory/total-impact-core