Remove is_remotestorage() call from VFS. We already have statvfs() there to handle...

Remove is_remotestorage() call from VFS. We already have statvfs() there to handle FS capabilities.

As discussed with Volker, it is better to calculate FS capabilities at
connection time. We already do this with help of VFS statvfs() call
which allows to fill-in system-specific attributes including FS
capabilities. So just re-use it if you want to represent additional
capabilities in your modules. The only caution is that you need to
call underlying statvfs() call to actually get system-specific
capabilities (and other fields) added. Then add module-specific ones.
(This used to be commit e342ca0d931f9a5c8ec9e472dc9c63f1fe012b3a)