v5.0.0

Breaking*

node >= 8
node >= 10.17

Bump minimum node version to v10.17.0 due to move-file #651

*If ncu was working for you on v4.x, then v5.0.0 will still work. Just doing a major version bump since ncu's officially supported node version is changing. v4 should be patched to be compatible with node v8, but I'll hold off unless someone requests it.