Update to new block interface (again)

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Release 0.3.0

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
I actually meant version 0.4.0

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Merge pull request #11 from djs55/update-block-interface

Update block interface
Merge pull request #12 from djs55/update-block-interface

Update block interface