Changes Cluster constructor to take string by const reference.
Changes exception message in Cluster::getNodeById to use boost::format.

The previous code would cause a segmentation fault if nodeId was greater than the string length, and the message now actually includes the ID.
C++ client: Adds VOLDEMORT_ prefix to all include guards.

This should minimize conflicts with other libraries.
C++ client: Changes VersionedValue::getVersion to return a const Version*.

By returning a non-const Version*, the semantic const-correctness was broken. You could not modify the pointer, but that didn't matter.
Makes Store::get and Store::getName const functions.

Also changes InconsistencyResolvingStore, RoutedStore and SocketStore implementations to be const.
C++ Client: bump maintenance version number.