Add a disclaimer about inaccuracies

https://www.pivotaltracker.com/story/show/74603852
[Delivers #74603852]
Add alpha notice and supported browsers

https://www.pivotaltracker.com/story/show/74604694
[Delivers #74604694]
Merge pull request #11 from sealevelresearch/add-disclaimer-and-alpha-notice

Add alpha notice, supported browsers, disclaimer