Update to new KV_RO signature

The new signature has 'read' taking an offset and a length, and
returning a list of buffers rather than a stream.

Signed-off-by: David Scott <dave.scott@eu.citrix.com>
Merge pull request #6 from djs55/new-kvro-read

Update to new KV_RO signature
bump to 1.2.0 and sync CHANGES
Generate correct signature for V1.KV_RO