Do we want to add this dependency in core? I thought we'd add it in a separate module and use reflection to instantiate `HazelcastDataGrid` (or the `HazelcastBrooklynStorageFactory`, or more likely a `ReflectiveBrooklynStorageFactory` that can take the classname + some config)?

Feels nice to keep dependency separate. But if it's the only impl we'll have for a long time then not too bad just putting it in core...