Fix Travis

Author: rattrayalex

.travis.yml

@@ -1,13 +1,13 @@
 language: node_js
 node_js:
-  - '4'
   - '6'
   - '7'
 
 before_script:
   - npm run build
   - npm link
   - npm link babel-plugin-lightscript
+  - npm run build
 
 notifications:
   email: false

package.json

@@ -10,7 +10,7 @@
     "test": "mocha test",
     "test:debug": "node --inspect --debug-brk mocha test",
     "build": "babel src --out-dir .",
-    "prepublish": "npm run build && npm test"
+    "preversion": "npm run build && npm test"
   },
   "author": "Alex Rattray <rattray.alex@gmail.com> (http://alexrattray.com/)",
   "homepage": "http://lightscript.org/",