Fix the form rendering - first step

So here is my pull request about the HTML/CSS modifications I did during the OpenChateau and this evening.

The design of the objects creation form is better. 
Still things to do on the rendering of specific URIs, will be done during the week (maybe tomorrow)

Big next step, to make URIs to disappear for the user ;-)

![design-fixes](https://cloud.githubusercontent.com/assets/356084/5445605/871bbef6-84b5-11e4-8ae3-a0ef47c324f8.png)

PS: Qu'est-ce que tu en penses ?