Moving grunt validate-shrinkwrap from npm postinstall to Travis

.travis.yml

@@ -24,3 +24,6 @@ before_script:
 
 before_install:
   - sudo apt-get install libgmp3-dev
+
+script:
+  - grunt validate-shrinkwrap

package.json

@@ -9,7 +9,6 @@
     "test": "test"
   },
   "scripts": {
-    "postinstall": "./node_modules/.bin/grunt validate-shrinkwrap",
     "test": "NODE_ENV=dev node ./bin/db_patcher.js 2>/dev/null && NODE_ENV=dev ./scripts/gen_keys.js && NODE_ENV=dev ./scripts/tap-coverage.js test/local test/remote",
     "start": "NODE_ENV=dev scripts/start-local.sh 2>&1 | bunyan -o short",
     "test-mysql": "DB_BACKEND=mysql npm test",