Merge lp://staging/~gmb/launchpad/team-subscription-opt-out into lp://staging/launchpad/db-devel

All looks good, but perhaps there ought to be some tests for the basics, like adding to and removing from the store.

Some discussion on IRC. The following version is approved as patch-2208-58-0.sql:

-- Copyright 2011 Canonical Ltd. This software is licensed under the
-- GNU Affero General Public License version 3 (see the file LICENSE).

SET client_min_messages=ERROR;

-- A table to store subscription mutes in.

CREATE TABLE BugSubscriptionFilterMute (
    person integer REFERENCES Person(id)
        ON DELETE CASCADE NOT NULL,
    filter integer REFERENCES BugSubscriptionFilter(id)
        ON DELETE CASCADE NOT NULL,
    date_created timestamp without time zone
        DEFAULT timezone('UTC'::text, now()) NOT NULL,
    CONSTRAINT bugsubscriptionfiltermute_pkey PRIMARY KEY (person, filter)
);

-- We don't need an index on person, as the primary key index can be used
-- for those lookups. We have an index on just filter, as the bulk of our
-- lookups will be on filter.
CREATE INDEX bugsubscriptionfiltermute__filter__idx
    ON BugSubscriptionFilterMute(filter);

INSERT INTO LaunchpadDatabaseRevision VALUES (2208, 58, 0);