add .travis.yml

Author: chambart

.travis.yml

@@ -0,0 +1,12 @@
+language: c
+sudo: required
+install: wget https://raw.githubusercontent.com/ocaml/ocaml-ci-scripts/master/.travis-opam.sh
+script: bash -ex .travis-opam.sh
+env:
+  - OCAML_VERSION=4.02 TESTS=true
+  - OCAML_VERSION=4.03 TESTS=true
+  - OCAML_VERSION=4.04 TESTS=true
+  - OCAML_VERSION=4.05 TESTS=true
+os:
+  - linux
+  - osx