chore(build): switched build system to Gulp

Added:
- Replicated the build system using Gulp.
- Added "serve" task to spawn a webserver
- Webserver will listen for changes and auto-reload using liveReload
- Fixed https://docs.angularjs.org/error/$location/nobase
- Added correct 404 template

Missing:
- Karma unit test task

Run `gulp serve` to spawn the webserver and browse to `http://localhost:9000/example`.
All changes made in either the `example` folder or `src` folder will automatically reload the browser page.

No LiveReload browser extension required, gulp-connect uses https://github.com/mklabs/tiny-lr.