Do not leak Kryo from atomix.storage

Rather than dealing with Kryo serializers, introduce separate interfaces
to deal with input/output and serialization logic.

This allows us to be in explicit control as to what interface do we
support towards segmented journal persistence. It further means Kryo is
now a pure implementation thing and can be removed without changing the
APIs.

JIRA: CONTROLLER-2072
Change-Id: Ib4550f5f29d33d792f37110b5a14756654a5b87e
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>