update travis image
update travis image

axt/angr,iamahuman/angr,chubbymaggie/angr,axt/angr,schieb/angr,f-prettyland/angr,tyb0807/angr,angr/angr,angr/simuvex,iamahuman/angr,axt/angr,angr/angr,iamahuman/angr,schieb/angr,angr/angr,chubbymaggie/angr,chubbymaggie/angr,f-prettyland/angr,tyb0807/angr,schieb/angr,tyb0807/angr,f-prettyland/angr