Use gulp as build system (grunt's still there for now)
Add missing closing statement
:lipstick: Fix indentation
Streamline gulp build flow

Uses fewer steps.
:bug: Fix usemin directive in index.html

`main.css` will never be in the app folder, only the main.scss.
But `main.css` is in `dist` when build with gulp, and in `.tmp`
when build with grunt.
Add github pages deploy task
Enable travis to deploy to gh-pages