Refactored: moved to latest http-proxy, code reorganization, ...

**This PR implies the use of node 0.10**
Sorry for the one-commit-massive-PR.

# Repo / code management
* built sources live in a separate build/ folder
* npm start uses the built version
* npm test runs the tests against the built version
* coverage report lives in coverage/
* updated the Cakefile with the following commands: cake tests, cake build, cake coverage, cake lint, cake check-build

# Refactoring / code organization
* moved to americano
* DS accesses are handled by the americano-cozy plugin
* reworked the client code, it is now built with brunch
* https://github.com/mycozycloud/cozy-proxy/pull/39 has been integrated: signing out doesn't prevent the DS from encrypting/decrypting anymore
* emails are now sent through the DS
* websockets are now proxied on public routes

# UI
* the register form has been reworked
    * tooltips and validation information have been added
    * the user can now optionally choose a nickname and the timezone
* full localization. On the register page, it's based on browser's language

# Security 
* on a password reset, the key sent by email now has a TTL of 1 hour.
* websockets are now authenticated (not in public routes)

# Missing
* intense testing on the device component (manual and automated)
* understanding (and fixing?) why the very first request is so slow
* storing the session in a file or in the database to prevent losing it on proxy restart
* making the replication happens through the DS and not using Couch directly from the proxy (e.g. for the permission layer)