Merge pull request #204 from ocsigen/opam

[opam] add missing dependency on dune

Author: Zzull

ocsigenserver.opam

@@ -44,6 +44,7 @@ build: [
 install:[make "install.files"]
 depends: [
   "ocaml" {>= "4.08.1"}
+  "dune" {>= "2.7"}
   "ocamlfind"
   "base-unix"
   "base-threads"