The BlueSky lock manager is used to coordinate access to the same
filesystem among independent BlueSky processes.  As presently designed,
the lock manager itself is not fault tolerant nor meant for the wide
area.

TODO: Investigate whether there are any existing tools which could be
used instead.  Something like ZooKeeper might work, but is probably too
heavy-weight for now.


Objects can have small data values associated with them (i.e., version
number associated with an inode)

Cache states (for a single object):
    MESI?