Tell travis to download factorio

.travis.yml

@@ -1,3 +1,8 @@
 language: node_js
 node_js:
-  - "node"
+  - "node"
+before_install:
+  - sudo apt-get -qq update
+  - sudo apt-get install -y curl git tar
+  - curl -o factorio.tar.gz -L https://www.factorio.com/get-download/latest/headless/linux64
+  - tar -xvf factorio.tar.gz