Reboot client rendering: React + Pixi.js + RxJS

Here is a complete refactoring of all the client side code:
- **game rendering ported to Pixi.js.** efficient lib, remain a simple lib focused on rendering only.
- **game UI ported to React**. very productive and maintainable :-)
- **also using RxJS for handling streams** (and being able to control the speed of the game simulation while getting a server stream)

I have also added a NPM / Browserify stack.
The code is in `client/` . You can build it with **npm install** and **grunt**. 

It creates a bundle.js and a bundle.css to `/public/`. These files are not committed to avoid commit duplication and merge issues.

*For the production, `./client/build.sh` should be use (it compiles the source for production). I've put the steps in the main deploy script.*

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Features should be exactly identical as before (if not, it is a bug, I can fix it!),
+ added a play/pause feature + controlling the "speed control".

![screen shot 2014-08-04 at 23 48 25](https://cloud.githubusercontent.com/assets/211411/3804051/471bdd6a-1c21-11e4-8f30-110cf5e7b9f2.png)

(play with arrows and space bar).

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So now this refactoring is done, new features should be much more easier to add.

- My next idea is to make interpolation between game states to provide animations ;-)