Added support for mail digests

conf/application.conf.-example

@@ -51,6 +51,7 @@ yssdc{
     email{
       from = "info@example.com"
       noSubscriberContact = "foobar@example.com"
+      //optional: type = "digest" or type="vulnerabilities" (default); Digest is WIP.
     }
   }
   projects = {jobId:humanReadableName, …}

conf/evolutions/default/8.sql

@@ -0,0 +1,24 @@
+# --- !Ups
+CREATE TABLE "notification_digest_status" (
+  "user_provider_id" VARCHAR NOT NULL,
+  "user_provider_key" VARCHAR NOT NULL,
+  "last_changelog_id" INTEGER NULL
+);
+CREATE UNIQUE INDEX "notification_digest_status_user_idx" ON "notification_digest_status" ("user_provider_id","user_provider_key");
+
+INSERT INTO notification_digest_status
+(user_provider_id, user_provider_key, last_changelog_id)
+  SELECT
+    subscriber_provider_id  AS user_provider_id,
+    subscriber_provider_key AS user_provider_key,
+    (SELECT MAX(id) from change) AS last_changelog_id
+  FROM vulnerability_subscription
+  GROUP BY subscriber_provider_id, subscriber_provider_key;
+
+ALTER TABLE change ADD COLUMN "notified_to_somebody" BOOLEAN NOT NULL DEFAULT FALSE;
+UPDATE change SET notified_to_somebody = TRUE;
+
+# --- !Downs
+drop table "notification_digest_status";
+
+ALTER TABLE change DROP COLUMN "notified_to_somebody";