Add OSX to travis

Signed-off-by: Richard Bonhomme <tincanteksup@gmail.com>

.travis.yml

@@ -1,15 +1,18 @@
-language: bash
+matrix:
+  allow_failures:
+  language: bash
+  sudo: false
+  include:
 
-os: linux
-dist: bionic
+    - os: linux
+      dist: bionic
+      script:
+        - openssl version
+        - shellcheck --version
+        - bash -c 'export SHELLCHECK_OPTS="-S warning -e SC2006"; shopt -s globstar; shellcheck **/*.sh easyrsa3/easyrsa'
+        - sh op_test.sh -vv
 
-sudo: false
-
-env:
- - PATH=/usr/bin:/bin:./:/usr/local/bin
-
-script:
- - openssl version
- - shellcheck --version
- - bash -c 'export SHELLCHECK_OPTS="-S warning -e SC2006"; shopt -s globstar; shellcheck **/*.sh easyrsa3/easyrsa'
- - sh op_test.sh -vv
+    - os: osx
+      osx_image: xcode10.1
+      script:
+        - sh op_test.sh -vv