Add get tasks endpoint (#29)

Closes #20

Reviewed-on: #29

backend/db.go

@@ -182,3 +182,21 @@ func (db *Db) CreateTask(task *CreateTaskRequest) (int, error) {
 
 	return lastId, nil
 }
+
+func (db *Db) GetTasks() ([]Task, error) {
+	tasks := make([]Task, 0)
+	var err error
+
+	for row := range db.db.Query("select id, name, reward, assigned from tasks").Range(&err) {
+		task := Task{}
+		err = row.Scan(&task.ID, &task.Name, &task.Reward, &task.Assigned)
+		if err != nil {
+			return nil, err
+		}
+		tasks = append(tasks, task)
+	}
+	if err != nil {
+		return nil, err
+	}
+	return tasks, nil
+}