Try to fix travis

.travis.yml

@@ -27,6 +27,19 @@ node_js:
   - 5
   - 6
 
+# Install a C++11 compatible compiler
+addons:
+  apt:
+    sources:
+      - ubuntu-toolchain-r-test
+    packages:
+      - gcc-4.8
+      - g++-4.8
+
+# Set C++ compiler as default
+env:
+  - CXX=g++-4.8
+
 # Cache dependencies
 cache:
   pip: true