[jvstm-cluster] Add getNumMembers
[jvstm-common] Add method getId to VBox
[jvstm-common] Make VBox abstract (it was already used as such)

The VBox class is never instantiated.  So we mark it as such.
Bugfix: add RemoteCommit.toString()

This allows the logger in ClusterUtils.sendCommitInfoToOthers to be able to
abstract itself from what type of RemoteCommit we're using.  When the
SpeculativeRemoteCommit was added it had introduced a bug here.
[jvstm-common] Add OwnedVBox (previously VBox)

  * Abstract VBox ID.  Use the id instead of explicitly assuming the existence
    of a slotname and an ownerId.  OnwedVBox defines its ID based on these
    fields.
  * add method findVBox given its id: looks up a cached vbox.  Depending on
    the backend, the implementations will either use a VBox cache or the
    DomainObject cached (e.g. when the VBox is an OwnedVBox).
Merge pull request #152 from smmf/fix/log-remote-commit

Bugfix: add RemoteCommit.toString()
Merge pull request #153 from smmf/feature/abstract-vbox-id

Feature/abstract vbox id
[jvstm-common] Update Repository interface
[jvstm-infinispan] Update Repository implementation
Merge pull request #154 from smmf/feature/update-repository-implementation

Feature/update repository implementation
[jvstm-common] Add StandaloneVBox
Create backend jvstm-datagrid

This backend adds support for running JVSTM on top of a (pluggable) data
grid.  It also includes an implementation for Infinispan.

E.g to use the Infinispan data grid one should provide the following
configuration:

    config.class=pt.ist.fenixframework.backend.jvstm.datagrid.infinispan.DataGridConfig
    dataGridClassName=pt.ist.fenixframework.backend.jvstm.datagrid.infinispan.InfinispanDataGrid

And optionally:

    dataGridIspnConfigFile=<the-ispn-config-file>
[jvstm-common] Implement StandaloneVBox.reload() and makeNew()
[jvstm-datagrid] Update Repository implementation
Merge pull request #155 from smmf/feature/jvstm-datagrid

Feature/jvstm datagrid