Fix read property set observe bug

[hidetak]

There was a bug in the process of setting observe for a Read Property node.

• When a Read Property node is placed on the canvas, the configuration screen of the node is displayed, and the Thing is selected, one property is selected, but the observe checkbox is not displayed even if the property is observable.
• When observe is true in Read Property and a non-observable property is selected, the observe checkbox is hidden, but observe remains true internally, so when the flow is deployed, an error message stating that it cannot be observed is displayed. After deploying a flow, an error message stating that the flow is unobservable will be output all the time.
• When creating a flow from Create WoT Consumer flow, observe was true for the read-property node created, even though the property observable defined in the TD was false.
• In flows generated by the Create WoT Consumer flow plugin, bool values were being converted using String(value), resulting in an error message stating that the type was different.Fixed to use JSON.parse(value) for conversion.

[egekorkan]

Looks good on my side! Thanks @hidetak :)

I will do a PR to update the node-wot version and then we can make a new release.