ability to put a whole server in read-only mode

In order to allow for the smoothest transition to the new platform, i'd need the ability to put a whole server in read-only mode.

Would it be possible to make the "edit" and "edit objects" options disappear if xwiki.readOnlyMode is true in the configuration file ?

This may also prove useful later for implementing features such as basic mirroring in a load-balancing master-slaves cluster.