Merge branch 'chore/cassandra-subscription-request-schema' into 'master'

    WHERE user_guid IS NOT NULL AND domain IS NOT NULL

    WHERE user_guid IS NOT NULL AND domain IS NOT NULL

    PRIMARY KEY (domain, user_guid)

    PRIMARY KEY (domain, user_guid)

    WITH CLUSTERING ORDER BY (user_guid ASC);

    WITH CLUSTERING ORDER BY (user_guid ASC);

CREATE TABLE minds.subscription_requests (

    publisher_guid bigint,

    subscriber_guid bigint,

    timestamp timestamp,

    declined boolean,

    PRIMARY KEY (publisher_guid, subscriber_guid)

);

CREATE TABLE minds.notification_batches (

    user_guid varint,

    batch_id  text,

    primary key (user_guid, batch_id)

);