include osx in travis build

.travis.yml

@@ -1,14 +1,20 @@
-language: python
-python:
-  - "2.7"
 
-addons:
-  apt:
-    packages:
-    - cmake
-    - pyqt4-dev-tools
+matrix:
+  include:
+    - os: osx
+      language: generic
+      before_install:
+        - brew update
+        - brew install libxml2 qt qt4 pyqt5
+    - os: linux
+      dist: trusty
+      sudo: required
+      language: python
+      python: 2.7
+      addons:
+        apt:
+          packages:
+            - cmake
+            - pyqt4-dev-tools
 
-# command to install dependencies
-#install: "pip install --user -r requirements.txt"
-# command to run tests
 script: make all