Remove node v0.10, v0.12 and iojs from travis builds
Remove node v0.10, v0.12 and iojs from travis builds

Builds are failing due to incompatible javascript versions. Plus the versions have been deprecated.

joelpurra/getdns-node,joelpurra/getdns-node,joelpurra/getdns-node,getdnsapi/getdns-node,getdnsapi/getdns-node,getdnsapi/getdns-node