add basic http server with health check endpoint

Sorry for not using GerritHub. There’s a bug where it won’t let me send out a review because ![my email is null](https://f.cloud.github.com/assets/365204/2215276/06fc4204-99ec-11e3-8942-9731ab1bcb18.png) but I can’t edit my email address :(

I’ve sent a note to them hoping they fix it soon.
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In any case, a server for your consideration.