remove travis slack notifications
remove travis slack notifications

Revoked the token on slack as well, so people searching the history won't find it.
angelicaochoa/cbioportal,pughlab/cbioportal,mandawilson/cbioportal,d3b-center/pedcbioportal,d3b-center/pedcbioportal,onursumer/cbioportal,mandawilson/cbioportal,cBioPortal/cbioportal,cBioPortal/cbioportal,sheridancbio/cbioportal,n1zea144/cbioportal,angelicaochoa/cbioportal,sheridancbio/cbioportal,onursumer/cbioportal,d3b-center/pedcbioportal,pughlab/cbioportal,cBioPortal/cbioportal,onursumer/cbioportal,zhx828/cbioportal,cBioPortal/cbioportal,onursumer/cbioportal,zhx828/cbioportal,angelicaochoa/cbioportal,onursumer/cbioportal,angelicaochoa/cbioportal,mandawilson/cbioportal,d3b-center/pedcbioportal,d3b-center/pedcbioportal,zhx828/cbioportal,n1zea144/cbioportal,pughlab/cbioportal,onursumer/cbioportal,angelicaochoa/cbioportal,cBioPortal/cbioportal,zhx828/cbioportal,sheridancbio/cbioportal,n1zea144/cbioportal,pughlab/cbioportal,mandawilson/cbioportal,sheridancbio/cbioportal,d3b-center/pedcbioportal,pughlab/cbioportal,n1zea144/cbioportal,mandawilson/cbioportal,angelicaochoa/cbioportal,n1zea144/cbioportal,zhx828/cbioportal,zhx828/cbioportal,zhx828/cbioportal,n1zea144/cbioportal,n1zea144/cbioportal,sheridancbio/cbioportal,angelicaochoa/cbioportal,mandawilson/cbioportal,sheridancbio/cbioportal,pughlab/cbioportal,cBioPortal/cbioportal,mandawilson/cbioportal,d3b-center/pedcbioportal,pughlab/cbioportal