Add AngularJS to client, with Browserify setup, refs T604

Summary:
- add ng, browserify, and brfs for single file packaging
- automatically install bower dependencies with npm
- make `www/` the build directory, ignore compiled css and js
- configure package.json for browserify builds
- update gulp setup to copy font-awesome fonts into build
- add `app/` directory for js and views

Test Plan:
```
npm install
npm run build
```

Load client in browser, click any post title to go to (stub) detail page, click home to go back.

Todos:

- rebuild `www/js/app.js` actions with Angular
- reconfigure docker nginx server for pushState support
- include `.htaccess` instructions in README for pushState support
- integrate browserify build with gulp watch (see https://github.com/gulpjs/plugins/issues/47)
- figure out why watchify is not working

Reviewers: shadowhand, seth

Reviewed By: seth

Subscribers: eyedol, bodacea, digitalafrican, srutto, dkobia

Differential Revision: https://phabricator.ushahidi.com/D269