Handle Echoes

[mnwalker]

Currently the receiver is set to skip all message_echoes webhooks.
As a default this is great since this is normally sent by the app so no need to handle.

But I have situations where certain users need to send messages directly from the facebook interface, which results on their reply not showing inside the app.
If could enable a config option to skip echoes, default true, then we could handle this and avoid duplication through our app.

Not seen any updates for a while, happy to build a pull request if this plugin is still being maintained and this config option would be acceptable.

[CasperLaiTW]

Hi @mnwalker

Thanks for feedback, I don't have too much time to maintain the repository right now.

Welcome to PR or fork to make your library :)