Bugs #5635 & #5743 - Fixing a problem of file upload on Web browsers that are not featured with the JavaScript File API :

- adding a new system in order to decode easily the request parameters and put them automatically into a PoJo
Also :
- fixing upload of a file with some accents in its name)
- fixing attachment creation in multilingual context (it was always created in FR language)
- fixing FileUpload plugin that was not working with security tokens and old web browsers