Making this EJS 2.0.0 compatible

[straker]

I'd like to make this repo work with EJS 2.0.0. I figured out the changes that would need to happen to make that work so would be more than happy to make a PR.

Would you be interested in supporting EJS 2.0.0? And if so, would you be ok with a breaking change and a major version bump, as well as dropping EJS 1.0.0 support from master? Or if you'd prefer, I can make it support both EJS versions, but it'll basically have to bring back the options.__proto__ magic that EJS 1.0.0 did but that EJS 2.0.0 no longer does.