Cache modules on Travis.

RubenVerborgh · RubenVerborgh · commit 5d83f6695e13 · 2016-09-28T15:13:28.000+02:00
diff --git a/.travis.yml b/.travis.yml
@@ -14,3 +14,6 @@ addons:
       - ubuntu-toolchain-r-test
     packages:
       - g++-4.8
+cache:
+  directories:
+    - node_modules
