Update .travis.yml

Shouldn't fail to compile LevelDown anymore

.travis.yml

@@ -1,11 +1,23 @@
 language: node_js
+
 node_js:
 - '5'
 - '5.1'
 - '4'
 - '4.2'
 - '4.1'
 - '4.0'
+
+env:
+  - CXX=g++-4.8
+
+addons:
+  apt:
+    sources:
+      - ubuntu-toolchain-r-test
+    packages:
+      - g++-4.8
+
 deploy:
   provider: npm
   email: [email protected]
@@ -14,6 +26,7 @@ deploy:
   on:
     tags: true
     repo: musiqpad/mqp-server
+
 notifications:
   slack:
     secure: 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