Transaction implementation (#2)

Reviewed-on: #2

dbconnection.go

@@ -36,6 +36,10 @@ func (c *DBConnection) Prepare(sql string) (*sql.Stmt, error) {
 	return c.db.Prepare(sql)
 }
 
+func (c *DBConnection) Begin() (*sql.Tx, error) {
+	return c.db.Begin()
+}
+
 func (c *DBConnection) Close() (bool, error) {
 	err := c.db.Close()
 	if err != nil {