added optional days back variable and fixed contributor structure
added optional days back variable and fixed contributor structure

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