Update meta tags for Embed

A buddy of mine contacted me regarding my experience at gSchool - he's curious about joining a school - and I sent him a link via Facebook Messages --- this is what showed up:

![screen shot 2014-09-03 at 10 37 59 am](https://cloud.githubusercontent.com/assets/1141717/4136701/8cd34cfa-3380-11e4-8a58-4b9e37c77b8b.png)

Went ahead and pulled some of the source from ovenbits.com to set some Open Graph tags (and add an image for the `og:image` tag).

Even though I run `rackup` -- I can't seem to get site to work locally (I just get a 404) -- so, I haven't been able to test how the actual embed works.

You can test it here, though: https://developers.facebook.com/tools/debug/og/object?q=turing.io

Or - if you can give me a quick rundown on what's different with running the site locally - I'll test myself & make adjustments.

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Also - updated the `.ruby-version` file to match the `Gemfile`