(#70) - add Futon UI

Futon is now served from `/_futon`.  All I did here was copy over the HTML/JS/CSS files from CouchDB 1.6.0.  I also had to add a few stub methods so that Futon wouldn't throw an error and complain.

The "verify installation" button works too.  :)

![screenshot 2014-07-07 13 09 25](https://cloud.githubusercontent.com/assets/283842/3501129/0cacf4bc-0613-11e4-8fdc-2a2c5a75d16e.png)