ci: Update CI scripts

The changes in Boost 1.62 broke command-line invocation of unit tests

Change-Id: Id98d00f5f85b2154981dec859c8c5a671ec06c84
diff --git a/.travis.yml b/.travis.yml
index 0e7b265..127eddf 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,14 +1,24 @@
 sudo: required
 language: generic
-os: linux
-dist: trusty
-compiler:
-  - gcc
+matrix:
+  include:
+    - os: linux
+      dist: trusty
+      env:
+        - CXX=g++
+        - NODE_LABELS="Linux Ubuntu Ubuntu-14.04"
+    - os: linux
+      dist: trusty
+      env:
+        - CXX=clang++
+        - NODE_LABELS="Linux Ubuntu Ubuntu-14.04"
+    - os: osx
+      env:
+        - CXX=clang++
+        - NODE_LABELS="OSX OSX-10.9"
 notifications:
   email:
     on_success: always
     on_failure: always
-env:
-  - NODE_LABELS="Linux Ubuntu Ubuntu-14.04"
 script:
   - ./.jenkins