jbuilder is not available

[voila]

Following the README,

make build fails with:

`make: jbuilder: Command not found`

trying to install jbuilder with opam fails with:

`[ERROR] jbuilder is not available because your system doesn't comply with ocaml-version >= "4.03.0".`

[jordwalke]

So you are not on 4.03+ ?
What version are you on and how did you install ocaml?

[voila]

I am on 4.02.3+buckle-master via opam. Is 4.03.0 required ?