Switch to Trusty for the TravisCI builds
Switch to Trusty for the TravisCI builds

This should allow the installation of Rubinius and running the tests
on it (which has been broken for a while on the Precise images).

urbanautomaton/rubocop,haziqhafizuddin/rubocop,tdeo/rubocop,deivid-rodriguez/rubocop,petehamilton/rubocop,smakagon/rubocop,bbatsov/rubocop,palkan/rubocop,panthomakos/rubocop,mikegee/rubocop,tdeo/rubocop,maxjacobson/rubocop,meganemura/rubocop,bbatsov/rubocop,sue445/rubocop,sue445/rubocop,scottmatthewman/rubocop,b-t-g/rubocop,petehamilton/rubocop,jfelchner/rubocop,scottmatthewman/rubocop,mikegee/rubocop,petehamilton/rubocop,jmks/rubocop,alexcstark/rubocop,jfelchner/rubocop,akihiro17/rubocop,maxjacobson/rubocop,tdeo/rubocop,tejasbubane/rubocop,bquorning/rubocop,akihiro17/rubocop,vergenzt/rubocop,b-t-g/rubocop,vergenzt/rubocop,panthomakos/rubocop,deivid-rodriguez/rubocop,tejasbubane/rubocop,deivid-rodriguez/rubocop,maxjacobson/rubocop,bquorning/rubocop,rrosenblum/rubocop,haziqhafizuddin/rubocop,jmks/rubocop,mikegee/rubocop,urbanautomaton/rubocop,vergenzt/rubocop,tejasbubane/rubocop,smakagon/rubocop,jmks/rubocop,bquorning/rubocop,pocke/rubocop,jfelchner/rubocop,palkan/rubocop,lumeet/rubocop,rrosenblum/rubocop,akihiro17/rubocop,alexcstark/rubocop,meganemura/rubocop,lumeet/rubocop,rrosenblum/rubocop,sue445/rubocop,palkan/rubocop,pocke/rubocop,panthomakos/rubocop,meganemura/rubocop