Don't pull in all of nautilus for the -extensions subpackage
    
    The -extensions subpackage that ships libnautilus-extension.so.1
    currently has a hard dep on the main nautilus subpackage. This is
    problematic because it causes anything that links with
    libnautilus-extension.so.1 to automatically pull in all of nautilus.
    
    With the current appdata and gnome-software setup, we don't want to have
    one gui app ever depending on another gui app.
    
    As a fix, just drop the nautilus dep from nautilus-extensions and allow
    the libraries to be installed standalone.