added collision category
added collision category

erinspace/scrapi,mehanig/scrapi,erinspace/scrapi,felliott/scrapi,alexgarciac/scrapi,fabianvf/scrapi,jeffreyliu3230/scrapi,fabianvf/scrapi,icereval/scrapi,felliott/scrapi,CenterForOpenScience/scrapi,ostwald/scrapi,mehanig/scrapi,CenterForOpenScience/scrapi