Remove ruby-head from travis setup
Remove ruby-head from travis setup

JustMikey/virtus,artemeff/virtus,baojjeu/virtus,XescuGC/virtus,solnic/virtus,hapiben/virtus,macressler/virtus,dslh/virtus,faucct/virtus,mallikarjunayaddala/virtus,reevoo/virtus