Improve filesystem mapping

Mapping a Nuxeo repository to a filesystem is not an easy job because the models do not match correctly:

• name vs title+filename+name
• file+folder vs folderish doc + multiple attachements

Most existing filesystem mapping protocol implementations in Nuxeo have tried to solve this issue: WebDav, WSS and CMIS.

There is no ideal solution and we will have to add some constraints on top of the Nuxeo model.

Rather that continuing with several mapping logic, it's time to build a generic module that will handle all the work:

• Nuxeo Document -> Filesystem resource
• File System resource -> Nuxeo Document (including what is done via FileManager)
• Listeners to enforce the limitations of the FS model

This new module should be integrated in WebDav, WSS and CMIS.