Remove server side content and test

We have pivoted and decided that the application will be a client side application based on top of HTML5 localStorage and/or the new Dropbox Datastore API.
The server.js stay here in order to easily serve our static file.
remove dependencies to mocha

mocha was used for server side unit test. As we don't have server side anymore... :)
Merge pull request #17 from avernois/remove_server_side

Remove server side