chore: disable npm install on Travis
chore: disable npm install on Travis

Grunt is configured to run `npm install` before every task. That is convenient when switching a branch for example.

On Travis, this makes no sense and is causing tons of NPM warnings (eg. packages not defining repository field etc).

ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js,ggershoni/angular.js