Title: Configuring the Object Storage Service Storage Nodes

Describe the issue:
In the 1. and 2. step it is written that we should use ext4 or xfs filesystems, but it is not written, that swift's object server will make error messages in /var/log/messages if the filesystem is not mounted with extened attributes, like this:

Jun 21 18:02:49 localhost object-server ERROR __call__ error with PUT /1/198/AUTH_0462cfe859364e2e92a1f78309576d02/c1/data1.file : #012Traceback (most recent call last):#012  File "/usr/lib/python2.6/site-packages/swift/obj/server.py", l
ine 928, in __call__#012    res = method(req)#012  File "/usr/lib/python2.6/site-packages/swift/common/utils.py", line 1558, in wrapped#012    return func(*a, **kw)#012  File "/usr/lib/python2.6/site-packages/swift/common/utils.py", line 520, in _timing_stats#012    resp = func(ctrl, *args, **kwargs)#012  File "/usr/lib/python2.6/site-packages/swift/obj/server.py", line 705, in PUT#012    file.put(fd, metadata)#012  File "/usr/lib64/python2.6/contextlib.py", line 34, in __exit__#012    self.gen.throw(type, value, traceback)#012  File "/usr/lib/python2.6/site-packages/swift/obj/server.py", line 284, in mkstemp#012    yield fd#012  File "/usr/lib/python2.6/site-packages/swift/obj/server.py", line 705, in PUT#012    file.put(fd, metadata)#012  File "/usr/lib/python2.6/site-packages/swift/obj/server.py", line 309, in put#012    write_metadata(fd, metadata)#012  File "/usr/lib/python2.6/site-packages/swift/obj/server.py", line 90, in write_metadata#012    setxattr(fd, '%s%s' % (METADATA_KEY, key or ''), metastr[:254])#012IOError: [Errno 95] Operation not supported (txn: txf14f4569d5d24609871a8c0f513dd733)

Suggestions for improvement:
Add a note to mount the filesystem with user_xattr option.