Metalsmith + Gulp

Goodbye Docpad and Grunt.

Take a look at the [gulpfile](https://github.com/goodeggs/bites/blob/3fecbbd18c27ba02fbf690eb60022bc00053487d/gulpfile.coffee) and the [metalsmith file](https://github.com/goodeggs/bites/blob/3fecbbd18c27ba02fbf690eb60022bc00053487d/metalsmith.coffee) to see what life would be like in this new world. The [README](https://github.com/goodeggs/bites/blob/3fecbbd18c27ba02fbf690eb60022bc00053487d/README.md) shows the new commands for common use, pretty much like the old commands.

The only visible change to the site is that copy text now uses the `Graphik` webfont.  It was in there before but the link was screwy.  I've integrated a crawler to catch this things in the future.  More on that below.

The [integration spec setup](https://github.com/goodeggs/bites/blob/3fecbbd18c27ba02fbf690eb60022bc00053487d/spec/post.spec.coffee) (mocha-fibers + wd + chai-as-promised) is my proposal for the ideal-integration-spec-setup-fight-to-the-death coming soon to a tech-talk near you :rage4: @bobzoller.

What's new?
----------------
I find [gulp](https://github.com/gulpjs/gulp/) and [metalsmith](https://github.com/segmentio/metalsmith) much easier to follow than grunt and docpad, but that's pretty fuzzy.  This PR adds a bunch more.  Happy to split into smaller PRs and discuss individually if folks have strong feelings.

- edit-refresh cycle is much faster while writing a new post
- a generator for new posts: `gulp new:post` (we should add another for author pages & wire them together)
- a few webdriver based integration tests: `gulp mocha`
- a site crawler that checks for broken links & asssets: `gulp crawl`
- travis integration that runs both, so our branch, PR, publish flow gets link checking for free and could be pretty easily hooked up to do #32
- gulp-gh-pages fixes #37.




Thoughts?