typos + rephrasing + not translated text

- a lot of typos and rephrasing 
- an big mistranslation about "Box" Cloud Service, whose name mustn't be translated to French.

Attached, an other screenshot of text that is in native language in app, without being in strings.xml file for localization purpose.

![Screenshot_2013-02-05-08-34-28](https://f.cloud.github.com/assets/3460127/126781/c7e8cf78-6f72-11e2-9c9d-fbd150beb8f3.png)