Branch b1_4_mountconf

Branch b1_4_mountconf
b=8007
Hunt down some memory leaks:
1. There are problems with the llog_finish/init pair in mds_lov_add_ost.
   Firstly, they must be atomic as a pair.
   Secondly, the setup sets up more than the cleanup cleans up (see
   note in llog_setup), so we hackishly fix that.
2. Make sure we don't exit the umount until after we've dropped all our
   references to the mount.  Class_cleanup isn't synchronous, and we can't
   exit the umount and risk our sb getting destroyed until we're really done.
   So added a polling check.  Also, move the MDS/OSS cleanup check until after
   the poller, since I'm just looking at the class refcount.