Implement Repository.reloadAttributeSingleVersion for jvstm-datagrid and jvstm-ispn
Bugfix: Use notLoadedBody instead of NOT_LOADED_BODY

  * There was a bug when using StandaloneVBoxes.  The NOT_LOADED_BODY was
    being used to put null in its 'value', when an unexisting StandaloneVBox
    was requested.  This was so that 'null' could be returned to the
    programmer without ever creating that box.  This is ok, because if a
    commit ever occurs to this box, it is correctly applied in front on this.
    However, the problem was that, because the NOT_LOADED_BODY was shared
    (!!!) when we set null in this body we were destroying all other uses of
    the NOT_LOADED_BODY.  The downside to the current solution, is that the
    instance is no longer shared, so it's memory space isn't saved.  Later, we
    may want to improve this.
Clarify the difference between a loaded body and a valid body

  * A valid body is any body that either is not null or is not the special
    body with version=0 and value=NOT_LOADED_VALUE.  A loaded body is a body
    whose value is not NOT_LOADED_VALUE regardless of the version.
Add single body reload feature to vbox (reload + new API for Repository)
[jvstm-lf] Replace recursive with iterative loadVersionsInRange

  * Prevents StackOverflowException

  * Also Rename DataVersionHolder to DataHolder (versions were no longer being
    kept there)
[jvstm-lf] No need to start a transaction to create a cache
[jvstm-lf] Fix commit helping wrt. setting the txVersionMap
[jvstm-lf] Save and restore current tx from context when committing a request
[jvstm-lf] Fix: updateOrecVersion in LocalCommitOnlyTransaction now redirects to decoratedTx
[jvstm-lf] Bugfix: 3 problems regarding helpCommit

  * Make txVersionToCommitIdMap static. It was a Map per commit instance!!!
    duh

  * Override helpCommit in LockFreeTransaction.  Needed to write to the
    persistence the map {txVersion}->{commitId} when THIS tx is doing local
    validation before deciding to broadcast its commit request

  * Don't throw commit exception when just helping to commit some tx during
    processCommitRequests in the beginning of a LockFreeTransaction.
[jvstm-lf] Several fixes to InitTransaction algorithm and local validation sequence
[jvstm-lf] Upgrade to hazelcast 3.0-RC1

  * This is required to ensure Total Order.

  * Also, for testing, I'm using a ReentrantLock onMessage for the commit
    topic
[jvstm-cluster] Upgrade to hazelcast 3.0-RC1
Minor: Fix spelling
[jvstm-lf] Bugfix: Remove reference to 'this' in helpCommit

  * This could lead to mapping the wrong txVersion->commitId.  Actually, it
    only worked when the helping transaction was helping itself.  Serious
    problem, hard to notice.
[jvstm-lf] Add CommitHelper thread and better shutdown

  * The commit helper thread ensures that even if nothing is happening on the
    system (no txs running in any node), a new member will still be able to
    join, because there will be someone (this helper thread) dealing with
    commit requests. (New members use the InitTransaction to syncronize their
    version.

  * Invoke clear() on static maps to enable reuse of the Framework after a
    shutdown().