Implement gedmo translation

Here is first step with gedmo system.

Compare to previous bundle I added
- Configuration : You can configure the list of translation locales and the default one
- twig extension to check if object is translatable
- base model so I can adapt for PHPCR and others later

I changed branch alias to 1.0.*  like the SEO bundle what to you think about that ?

So next I'll change my Presta bundle to fit this and right doc.
Then I'll do the same for PHPCR