Remove the generated prefixes in CSS files

All the CSS rules contain a prefix once deployed. That makes each rule more precise by adding a selector like .galaxy*** or .print***. It was originally made to be sure that the CSS rules from Nuxeo will be stronger than CSS rules from the libraries we use (RFaces, jQuery, etc ..).

Now that a user is allowed to add its own rules in the CSS editor from Studio, the prefixes from the platform are always stronger than the custom CSS from Studio. The user is forced to define some really precise CSS rules for small things, it is loosing a bit the sense of a simple customization.