Publish new gh-pages with every release

* Updates the gh_pages folder so it can stand alone
* Use release-it to push to gh-pages on every release

Other small tweaks:

* Use grunt-release-it as a wrapper for release-it
* Move bower dependencies to vendor/ folder

@dylnuge @bigsley @yayalice
Actually, it's not the best way to go about things, but I think it's fine for now. We just bundle in all the libraries we need into `app.js` instead of including them properly. I'll change it later (someday) but it's not really part of this PR. I also missed the comment: d3 is used for horizon/sparkline tables.