travis: drop "iojs-" prefix from version names
travis: drop "iojs-" prefix from version names

craigcomstocks/node-ffi,skoky/node-ffi,node-ffi/node-ffi,craigcomstocks/node-ffi,Icenium/node-ffi,unrealsolver/node-ffi,skoky/node-ffi,Icenium/node-ffi,unrealsolver/node-ffi,unbornchikken/node-ffi,unbornchikken/node-ffi,unrealsolver/node-ffi,node-ffi/node-ffi,Icenium/node-ffi,node-ffi/node-ffi,unbornchikken/node-ffi,unbornchikken/node-ffi,skoky/node-ffi,Icenium/node-ffi,craigcomstocks/node-ffi,node-ffi/node-ffi,skoky/node-ffi,craigcomstocks/node-ffi,unrealsolver/node-ffi