Update travis not to use global gulp

.travis.yml

@@ -12,10 +12,8 @@ cache:
 before_install:
 - npm install -g jspm
 - jspm config registries.github.auth $JSPM_GITHUB_AUTH_TOKEN
-before_script:
-- npm install -g gulp
 before_deploy:
-- gulp build
+- npm run build
 deploy:
   skip_cleanup: true
   provider: script

package.json

@@ -7,7 +7,8 @@
   "scripts": {
     "test": "gulp lint",
     "postinstall": "jspm install",
-    "start": "gulp serve"
+    "start": "gulp serve",
+    "build": "gulp build"
   },
   "keywords": [
     "Swagger",