Fixes #15, 14: Add explanatory paragraph and HKDemoNow FB like button.

Changes made:
- Added the Facebook JS SDK to the top of the page after the body tag per the docs.
- Add box explaining the page with the paragraph from our FB Group.
- Add and bind a Flight component to the info box so that we can make it dismissable.

Test plan:
- Firefox Aurora and Safari on `python -m SimpleHTTPServer`.

![screenshot 2014-10-01 18 02 19](https://cloud.githubusercontent.com/assets/44190/4483963/aee2e412-49b6-11e4-946c-e4a30303e8a8.png)
![screenshot 2014-10-01 18 02 30](https://cloud.githubusercontent.com/assets/44190/4483964/aeed9a1a-49b6-11e4-8e43-c88b66a15b3b.png)

Known issues:
- In order for the Facebook like button to show up, you have to view the page on a local webserver and not just as a `file:///`.