Merge pull request #156 from radarhere/travis

Added Xcode 9 builds

.travis.yml

@@ -96,8 +96,20 @@ matrix:
       env:
         - PYTHON_VERSION=pypy-5.7
         - VENV=venv
-    # Default OSX (xcode image) is 10.11 (xcode 7.3.1) as of 2017-05-02
-    # See: https://docs.travis-ci.com/user/osx-ci-environment/#OS-X-Version
+    # Default OSX (xcode image) is 10.12 (xcode 8.3.3) as of 2018-03-29
+    # See: https://docs.travis-ci.com/user/reference/osx/
+    - os: osx
+      osx_image: xcode9.2
+      env:
+        - PYTHON_VERSION=3.5
+    - os: osx
+      osx_image: xcode9.1
+      env:
+        - PYTHON_VERSION=3.5
+    - os: osx
+      osx_image: xcode9
+      env:
+        - PYTHON_VERSION=3.5
     - os: osx
       osx_image: xcode8.3
       env: