Updated .travis.yml to do a full build

The current Travis config won't ever pass newly-added unit tests because it doesn't do an actual build from the updated source files. This just replaces the 

```- npm run lint
- npm test```

lines with `grunt`.

.travis.yml

@@ -5,8 +5,7 @@ before_script:
 - gem install sass
 
 script:
-- npm run lint
+- grunt
-- npm test
 
 after_success:
 - npm run codecov