Add the internal database schema

Signed-off-by: Petr Šabata <contyk@redhat.com>

db/schema.sql

@@ -0,0 +1,15 @@
+CREATE TABLE IF NOT EXISTS modules (
+	id        INTEGER PRIMARY KEY,
+	name      TEXT NOT NULL, -- foo-1.23-4, module NVR
+	state     TEXT NOT NULL  -- init, building, done, failed, locked
+);
+
+CREATE TABLE IF NOT EXISTS builds (
+	id        INTEGER PRIMARY KEY,
+	module_id INTEGER NOT NULL,
+	package   TEXT NOT NULL,    -- bar-42-1, SRPM NVR
+	type      TEXT NOT NULL,    -- rpm
+	task      INTEGER NOT NULL, -- koji task id
+	state     TEXT NOT NULL,    -- koji build states
+	FOREIGN KEY(module_id) REFERENCES modules(id)
+);