Support rich message objects

[geoffklee]

Hi - this a quick patch I wrote so that I could pass a whole message object to this node, rather than just text. This allows for setting of the 'quick_replies' attribute, for example, which can be quite useful.

The original behaviour of accepting text is preserved, so this should be a non-breaking change.

[CLAassistant]

All committers have signed the CLA.

[chughts]

I am allowing this, although if not used correctly there is a possibility that the check msg.payload.text may crash the flow it is used in.

[geoffklee]

Thanks! I'd be happy to make the patch more robust, if you have suggestions. I'm fairly new to javascript and node-red