Rename directory 'Block' to 'Storage'

This patch renames the 'Block' directory to 'Storage' in
the Haskell code base. The same rename was done in the
python code base earlier this quarter. We generalize the
name, because we needed a place for general storage
utility functions and storage code for other storage
types like for example file storage.

Signed-off-by: Helga Velroyen <helgav@google.com>
Reviewed-by: Thomas Thrainer <thomasth@google.com>
Storage utility functions for Haskell

In order to extend the Haskell version of the NodeInfo
query, we need some utility functions to deal with
disk templates and storage types.

Signed-off-by: Helga Velroyen <helgav@google.com>
Reviewed-by: Thomas Thrainer <thomasth@google.com>
Make NodeInfo (hs) accept arbitrary storage types

So far, the Haskell implementation of NodeInfo just
requests storage information about volume groups.
With this patch, storage info for abitrary storage
types can be requested.

Signed-off-by: Helga Velroyen <helgav@google.com>
Reviewed-by: Thomas Thrainer <thomasth@google.com>