Merge pull request #290 from realworldocaml/upgrade-ci

Fix 4.11 build which doesn't require beta anymore

Author: NathanReb

.travis.yml

@@ -18,4 +18,4 @@ env:
     - OCAML_VERSION=4.08
     - OCAML_VERSION=4.09
     - OCAML_VERSION=4.10
-    - OCAML_VERSION=4.11.0+trunk OCAML_BETA=enable
+    - OCAML_VERSION=4.11.1