updated travis for osx builds

Author: DonJayamanne

.travis.yml

@@ -1,15 +1,26 @@
 language: python
 
-python:
-  - 2.7
-
 sudo: false
 
 os:
   - osx
   - linux
 
+matrix:
+    include:
+        # Use the built in venv for linux builds
+        - os: linux
+          sudo: required
+          python: 3.5
+        # Use generic language for osx
+        - os: osx
+          language: generic
+# Perform the manual steps on osx to install python3 and activate venv
 before_install:
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew update          ; fi
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then brew install python3; fi
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then virtualenv venv -p python3; fi
+  - if [[ "$TRAVIS_OS_NAME" == "osx" ]]; then source venv/bin/activate; fi
   - if [ $TRAVIS_OS_NAME == "linux" ]; then
       export CXX="g++-4.9" CC="gcc-4.9" DISPLAY=:99.0;
       sh -e /etc/init.d/xvfb start;