MVP for custom rules support

migrations/sqlite3/6_customrule_table.sql

@@ -0,0 +1,15 @@
+-- +migrate Up
+-- SQL in section 'Up' is executed when this migration is applied
+
+create table custom_rules
+(
+    id               integer primary key autoincrement,
+    user_id          varchar(255) not null REFERENCES users (id) ON DELETE RESTRICT ON UPDATE RESTRICT,
+    extension        varchar(255),
+    language         varchar(255)
+);
+
+-- +migrate Down
+-- SQL section 'Down' is executed when this migration is rolled back
+
+DROP TABLE custom_rules;