Add SQL schema and DAO for SignedMarkRevocationList (#850)

* Add SQL schema and DAO for SignedMarkRevocationList

This gets saved every day so we're not concerned about history, meaning
we can dual-write and/or dual-read without concern. The structure here
is somewhat similar to the ClaimsListDao and related classes.

* Update the DB files

db/src/main/resources/sql/flyway/V70__signed_mark_revocation_list.sql

@@ -0,0 +1,31 @@
+-- Copyright 2020 The Nomulus Authors. All Rights Reserved.
+--
+-- Licensed under the Apache License, Version 2.0 (the "License");
+-- you may not use this file except in compliance with the License.
+-- You may obtain a copy of the License at
+--
+--     http://www.apache.org/licenses/LICENSE-2.0
+--
+-- Unless required by applicable law or agreed to in writing, software
+-- distributed under the License is distributed on an "AS IS" BASIS,
+-- WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+-- See the License for the specific language governing permissions and
+-- limitations under the License.
+
+create table "SignedMarkRevocationEntry" (
+   revision_id int8 not null,
+    revocation_time timestamptz not null,
+    smd_id text not null,
+    primary key (revision_id, smd_id)
+);
+
+create table "SignedMarkRevocationList" (
+   revision_id  bigserial not null,
+    creation_time timestamptz,
+    primary key (revision_id)
+);
+
+alter table if exists "SignedMarkRevocationEntry"
+   add constraint FK5ivlhvs3121yx2li5tqh54u4
+   foreign key (revision_id)
+   references "SignedMarkRevocationList";