You could give github.com/lextoumbourou/goodhosts a shot. It has a CLI that allows you to add/remove hosts from the /etc/hosts file easily. If you're a Javascript fella, you could also give github.com/feross/hostile a spin.
Disclaimer: I've never really used these tools. It always seemed trivial enough to edit my /etc/hosts file via sed/awk. Gives me the added advantage of being able to run the same command on a cluster of machines as well without any extra installations. But then, to each his/her own.