title: Restarting firebase queue when node process has crashed
body: <p>I'm using firebase-queue for running some simple tasks. Suppose a task has been picked up by a worker and its state has been updated as in_progress. Now node crashes and the worker exists no more. The next time I restart node, how can I make sure that the tasks that were earlier in_progress gets picked up by firebase-queue after the restart? I'm using specs where I have defined the <code>error_state</code>, <code>start_state</code>, <code>finished_state</code>, <code>in_progress_state</code> and <code>retries</code>.</p>