test osx on travis

we need to re-add the osx travis tests as our trial ended with circle-ci

.travis.yml

@@ -0,0 +1,23 @@
+env:
+  - USER=travis GO111MODULE=off
+
+os:
+  - osx
+
+sudo: false
+
+language: go
+
+go:
+  - 1.12.x
+
+script:
+  - df -h
+  - travis_wait make ci
+
+branches:
+  only:
+    - master
+
+matrix:
+  fast_finish: true